TunerMaxima3000

iTrader: (4)

Ok I finally got some solid answers. Had a nice long chat with Brian Cattman, as well as a bunch of research.

This is some of the information I've compiled, if you have anything to add, or are aware of anything that is incorrect, please inform me and I'll correct it.

The hope is at the minimum, this thread can work in conjunction with the Header thread>
http://forums.maxima.org/5th-generat...er-thread.html

Here's a couple useful Threads (to be updated as posted):
Dyno results, Y-Pipe differences, Cali/Fed Spec + more
Cattman Y-Pipe info Thread with Brian's Imput


First, Clearing up terms used in this thread:

Exhaust Manifold: The OEM manifolds
Headers: Aftermarket Exhaust Manifolds, these are a 3 piece design. They INCLUDE the Y-pipe, and 2 Exhaust Manifolds WITHOUT any catalitic converters on any of the components.
Y-Pipe: The pipe that joins the Exhaust manifold/headers into one collective exhaust pipe.
Pre-Cat: The Catalitic Converter(s) that is(are) located before the 'Main' Catalitic converter.
RIGHT BANK = The 3 cylinders that are against your firewall, when someone says 'right bank cat' or 'right bank headers' this is the location they refer to. The other common name is 'Rear bank', because it's located closer to the rear of the car/engine bay.
LEFT BANK = The 3 cylinders that are against your Radiator. Also known as 'Front bank"

Second, here are some pictures of your exhaust.
Exhaust Manifolds differ from 2000 to 2001 (EGR), and again from the 2002/2003 Exhaust Manifolds
Y-Pipes differ from 2000-2001, to 2002-2003.

The rest of the exhaust from the Y-Pipe back is the same for ALL 5th gens.

2000-2001 Exhaust Manifolds:




2000-2001 - Entire exhaust after the Exhaust Manifolds:



2000-2001 Y-pipe close up:



2002-2003 Y-Pipe Close up


1995-1998:

Aftermarket Y-Pipe replaces BOTH pre-cat's. The pre-cat's on the 1995-1998 were INTEGRAL in the Y-pipe, so replacing the Y-Pipe replaced both Pre-cats.

I don't have great information about the 1999 model year. This is when they shifted to Cali spec, I think the 1999 is the same as the 2000/2001 Ypipe, and the 1999/2000 Exhaust Manifolds are the same (EGR).
*Verification Needed

Update: -
- It seems the 1999-2000 FED spec had the same set up as the 1995-1998.
- 1999-2000 CALI spec were the same as the 2001 (Left bank precat was separate).
- 2001 Anniversary Edition - 2002, 2003 seem to be the only ones that had NO EGR.


2000/2001:

Aftermarket Y-Pipe replaces the Right Bank CAT,.

The stock Y-Pipe and Right bank cat are INTEGRAL.

The Left bank cat, (front bank) is removable, as shown in the FSM pictures I posted above.

Now, to answer one of the big questions I had:

Q: Why not just extend the Y-Pipe at the front so BOTH cats are replaced?

A1: The outlet of the Exhaust manifold is about 3 1/2" to 4", so you would need to use a cone shaped pipe to reduce the Exhaust Manifold flange size to standard Y-Pipe size. The cost of producing this would outweigh the benefits.

A2: On the Cattman Y-Pipe, The O2 sensor for the Right bank Cat (that is replaced by aftermarket Y-Pipe) hooks into the exhaust stream after the Left bank Cat. This causes the O2 to still read properly, assuming the Left bank cat is functioning. So replacing the front cat would require O2 sims, replacing the Y-Pipe by itself, does not require any additional components.

It has been confirmed that you DON'T need to extend the 02 wiring to install it in the new location.

2002/2003:

-Precats Bolt up to Stock Exhaust Manifold.
-Stock Y-Pipe is it`s own entity.
-Replacing the Y-Pipe does NOT replace your Cats.
- Replacing the Y-Pipe still shows similar gains when compared to the 1999-2001 Cali spec Y-Pipe(around 8-12 HP)*NEED VERIFICATION

-----------------------
One option, is to install one or two 'Hi-Flow' cat(s), if you can find one that is made for the 2000-2003. This would enable you to gain some benefit in HP without having to run O2 Sims, or install headers.

I want to make this clear, because it seems to be a common misconception:
Replacing/eliminating Cats is NOT going to give you big Power gains. Properly performing Cats don't actually impede exhaust flow as much as everyone thinks they do.
Of course, if your cat's plugged, or in rough shape, then YES replacing it or eliminating it will create noticable gains.

In short:
There's not much point in replacing the Cat(s), or installing a 'Hi-Flow Cat'. The benefit is just not worth the cost in most applications. Some may argue this, before you do, see the next sentance.

If you really want to eliminate both cats and get some more serious Power gains, save your pennies and buy headers, and O2 sims.


Another thing that I want to point out, that is not clearly stated anywhere I've found on the forum:

The aftermarket Header/Y-Pipe combination (headers) is practically THE SAME for 2000-2003, the only difference is, the 2000/2001 Fed spec have EGR, and as such, require a bung welded into the Headers, Cattman does this for an additional $20, but I don't think any other aftermarket headers offer that.

So, to clear up, 2000-2001 Fed spec NEED EGR hook up.
2001 Anniversary Edition - 2003 DON'T need EGR, so headers off a 2003 WILL fit a 2001 AE.


For reference, Cattman's HP gains for 2001 Automatic are around:
10-13HP - Y-Pipe only
18-22HP - Headers

---*Need HP numbers for 2002/2003 auto and manual please*---

Now, the Cost difference:
Y-pipe - $350
Headers (with YPipe) - $817 with forum discount

Please Keep in mind, you WILL need 02 sims if you go with Headers, that is additional cost. *Someone please let me know average price paid for those components, so I can include it.

Quick read:

If you're serious about gaining power, get the headers.
If you want easy, quick HP gains on the cheap, with no adverse effects to stock engine management, get the Y-Pipe.

Also a couple additional things to note:

-5.5 Y-Pipe is NOT interchangable with the 5th gen Y-Pipe
-95-98 Exhaust Manifolds WILL fit 1995-2003, hence, replacing the cats. However, it's been pretty much confirmed that doing this is pointless, the gains are not even measurable in most cases. And it also creates the obvious issue of 02 sensors again. As well, you need to have a 4th gen Y-Pipe, and I'm unsure about 02 installation on that application.


If anything I've mentioned seems incorrect, please let me know and I'll edit this post.

kukx30de

iTrader: (4)

And.... just in case someone wants Dyno information:
http://desertpearlmax2.homestead.com/fed_ypipe.html

Thanks! great write up OP.

2000_MAXIMA_KING

iTrader: (30)

Just adding that the 2000 y-pipe and 2001 y-pipe are not the same, maybe cali-spec are but the Fed Spec 2000 is different, both precats are on the y-pipe so an aftermarket y-pipe eliminates both precats as it does with the 4th gen Maxima.

TunerMaxima3000

iTrader: (4)

Link added to OP

Rods03Max619

iTrader: (5)

Nice write up....

TunerMaxima3000

iTrader: (4)

We need confirmation on this. I do recall reading something along these lines for the 1999-2000 FED spec, and then the 1999-2000 CALI spec had the separate Pre-Cat.

2000_MAXIMA_KING

iTrader: (30)

Yea thats true, and what confirmation do you need I have a 2000 Fed Spec and the y-pipe eliminated both precats, the cali-spec is just like the 2001 and up. Basically in 2001 Nissan decided to make all the Maximas emissions like the cali-spec.

CMax03

iTrader: (3)

ok??????

Chris Gregg

iTrader: (59)

I read it twice. Seems you say early on that on a 5.5 neither headers or y-pipe replace pre cats. Later you say in order to illuminate pre cats, just get headers and O2 sims. Maybe it's just late and I'm not reading it right, but that part seems contradictive.

TunerMaxima3000

iTrader: (4)

It's admittedly a sloppy post right now. Once I have clarification on a few things, and we've looked it over to make sure it's accurate, I'll try to clean it up so it can get linked with the Stickied Modification thread.

Need your guys proof reading and imput.

Chris Gregg, please let me know where exactly you found that confusion, I wrote it and fully understand it, I don't know where you get confused on that point please quote the parts that 'contradict' each other.

Chris Gregg

iTrader: (59)

"In short:
There's not much point in replacing the Cat(s), or installing a 'Hi-Flow Cat'. The benefit is just not worth the cost in most applications. Some may argue this, before you do, see the next sentance.

If you really want to eliminate both cats and get some more serious Power gains, save your pennies and buy headers, and O2 sims."

"2002/2003:

-Precats Bolt up to headers.
-Y-Pipe is it`s own entity.
-Replacing the Y-Pipe does NOT replace your Cats. Replacing the Y-Pipe still shows similar gains (around 8-12 HP)*NEED VERIFICATION"

And maybe I'm just reading into things, but it sounds like (in the first quote) you are saying the headers replace the pre-cats. I list the second quote just because, after reading the first, it sounds like a re-iteration that headers (NOT the Y-pipe) illiminates the pre-cats. Even though you say here that the pre-cats bolt up to headers, I found things to be muddy. Again, maybe it's just me.

TunerMaxima3000

iTrader: (4)

Aftermarket Headers DO replace the pre-cats.

I'll try to revise the comment about pre-cat's 'bolting' up to the headers, I can see how that may get confusing.

To verify, the cat's do 'bolt up' to the headers, inbetween the y-pipe and the headers on the 2002/2003.
However, the only efficient way to get rid of them is to purchase headers.
A y-pipe only replaces the y-pipe on the 2002/2003.

Chris Gregg

iTrader: (59)

Then perhaps it's more somantics. I read "headers" and interpret aftermarket performance exhaust manifolds. I read "exhuast manifold" and interpret stock/factory original exhuast manifold.

So, when you say pre-cats bolt up to "headers," you are really saying:
Pre-cats bolt up to the stock manifolds. Subsequently, headers (read aftermarket) replace pre-cats.

I'm not the brightest, but you indicated the purpose is to clarify. So, for my needing information presented at a 5th grade level, I'd ask that you avoid using the same term for two different things....differentiate header (aftermarket) with original equipment (exhuast manifold).

*After re-reading, I feel my post may have come across as hateful in tone or judgemental. NOT my intent! Great information, I just see how SO OFTEN such simple things continue confusion when someone is looking to be spoon fed. I appreciate and respect your effort to spoon feed the masses!

TunerMaxima3000

iTrader: (4)

Not taken that way, thanks for pointing that out. And you're absolutely correct, I'm sure many people will have that auto-link that headers = aftermarket and manifold = stock.

Edited again


If there's anything else you think I can correct to further clarify, please let me know

02AutoMax

Does anyone still use the warpspeed y pipe for the 5.5th gen?

Would it be worth the money in gains paired with an exhaust compared to just getting headers?

NmexMAX

iTrader: (22)

No.


No.

00Lightsout

I see the confusion...but I understand what he means about the cats;

Even though the precats are very restrictive on our cars, especially the left(front) precat, the best way to get the MOST gain possible with a bolt on system would be to run the FED Carb front stock header, or aftermarket FED header replacement, thus eliminating the front precat. Then bolt up the FED Y-pipe to that and the right(rear) header, all while running sims on your 02 sensors.....then call it a day.

doing this will keep the last(3rd) Cat in it's original place and MAY still pass the CA legal emissions all considering the engine is running in tip top shape!

note: IMO the precats are more restrictive than the 3rd(post y-pipe) cat. I have run a sealed system of air at 320 CFM through both very clean precats and have noticed a VERY LARGE LOSS in CFM's after the precats. I wish I knew what the CFM is on the stock precats! If you want the system to run with minimal restriction replace the 3rd cat with a high flow magnaflow cat, install the 02 sensor after that cat, and run a second high flow magnaflow cat after that 02 sensor and eliminate your resonator and dump your muffler...this should still pass CA smog and dB outputs with no questions asked. Generally the best HP gains are from the least restrictive exhaust systems; less bends, mandrel bent, larger diameter, purged welding seams, and an oversized collector, and flush flanges(1/32 over piping I.D.) after the flex-section. Remember that "backpressure" is a myth, pure myth for all properly seating exhaust valves within the head.

I am more of a fan of a custom set up, however not everyone can build their own system...I like and respect Cattman over most others, but I would rather build a full system myself to get the MOST out of a header-back exhaust system at a DIY price. In the end I spend about 1/3 the cost, and usually come out with more/similar HP gains because of better flow on a much larger diameter system.

After all this does anyone know the best places to pick up exhaust flanges online...I've 'exhausted' my local shops for special order parts, and their prices SUCK peanuts!

00Lightsout

http://desertpearlmax2.homestead.com/fed_ypipe.html

^^ I like this write-up....but don't understand why the Baseline HP shows 174, when it should show 227hp on the 20th(2001) and 222hp on the 2000. Was his car in need of maintenance before the write-up??

TunerMaxima3000

iTrader: (4)

This is a good idea, I thought of it too, but I researched it and it seems it's been done quite a few times on the 4th gens with almost NO difference. The truth is, stock pre-cats that are in decent shape don't actually restrict exhaust flow by any notable amount. It's when they get clogged up from improper engine controls or abuse, or more rarely, actual component break-down, that the Cat's become restrictive.

And in that case, you're still better off replacing them, or getting headers/y pipe.

CLIFF: The FED spec manifold swap is a waste of time

Seriously? After all you just stated in the post about exhaust sizing, etc, you seem to have a decent idea of engine dynamics. You must be joking maybe?

In either case, I'll clear it up: The OEM rating on an engine is at the FLYWHEEL of the engine.

The dyno reads WHP (Wheel Horse Power). There are large losses through the driveline, in actuallity, the car that is dyno'd in that link was putting down half-decent WHP numbers.

Mr. Blue Sky

iTrader: (1)

dunno if this has already been said, but in my 2000 fed spec maxima, the stock y-pipe/headers had no precat(that is a cali-spec creation, which was later accepted across the board, and added to new cars to this date). my car only came with one main cat from the factory. when I did the y-pipe, it was just a straight swap.

00Lightsout

gigidy!...someone is paying attention

Me personally, I would like to actually run a full custom y-pipe with;
- 2.5" header connections.
- collect to a single 3" collector and 3" high flow cat before the flex.
- install the two precat 02 sensors before the new 3" y-pipe high flow cat...
then install the two post precat 02 sensors after that first high flow cat.
- replace the last Cat with another high flow cat(to pass the CA sniffer test)
- and run no resonator and no muffler with 3" mandrel all the way to the back, or split before the gas tank with 2.5" piping and dump it downwards in front of the rear tires

NOTE: having a SPLIT exhaust causes the SMOG TEST CENTER to only be able to get a sniffer reading out of ONE tip...so split them and keep them further apart for best results

you can also incorporate the CA legal cat into your y-pipe, install the 02's in their proper places, and just run that
http://www.summitracing.com/parts/MPE-33007/

heyhi

I have a 02 maxima with cat back.Will headers change the sound? Will y pipe change the sound? I wanna gain some hp but I don't want my car to mmuch louder

george__

iTrader: (1)

Yeah y-pipe, headers etc will change sound

nestorlugo

iTrader: (11)

hope this fed spec pic of the y-with to precats integrated with in can remove the confusion of the fed 00-01 and 01 CALI SPEC

maximasicilian123

Im a little confused. As far as I know the 02 has a few precats and the precats take away from hp. From what ive read the y pipe wont eliminate any precats but will gain around 8 hp or so. My question is will I pass emissions with the y pipe and as far as sound will it be louder or will the sound be different but not louder.

Reason im asking is this kid with a Cadillac gutted his cats and I think he has y pipe n headers. You can hear the car a block away. I don't want anything like that

george__

iTrader: (1)

^
Mine has 2.5", Cattmn header + y-pipe... Not fart can loud just inside droning is super bad

DennisMik

iTrader: (2)

That picture above is a Fed spec exhaust. It has only 3 oxygen sensors. The fed spec has an O2 sensor after the main cat.

Cali spec has 4 oxygen sensors and they are all mounted in the y-pipe.

If you put a y-pipe on that eliminates the pre-cats, the exhaust will be a little louder, but not a lot.

With a Calispec car, like the 2002 is, when you remove the Nissan y-pipe, you should remove the bank 2 pre-cat and gut it out and reinstall. The y-pipes do not eliminate this one.

maximasicilian123

What of the 2 caused the droning? Headers or y pipe?

DennisMik

iTrader: (2)

The engine has 2 precats, one on each bank of the engine. And yes, they do take away some power.

All the y-pipes I've seen for the Cali spec cars (such as your 2002) will only eliminate the bank 1 pre-cat. They don't replace the bank 2 pre-cat because it is not built into the y-pipe like the Fed spec was. So gutting the bank 2 pre-cat is advised.

If the pre-cats were left alone and not removed, you would not see any increase in hp.

You will pass emissions with the pre-cats eliminated. At a cold start-up, the main cat doesn't work at full efficiency. The pre-cats work when they are cold. Once the main cat warms up (I've read different times for 2 to 10 minutes) the main cat will handle any hydrocarbons that comes its way.

The pre-cats eliminated, the exhaust will be a little louder and the tone will be different, a little lower.

That kid probably eliminated the main cat, too.

maximasicilian123

Will the 02 sensors mount rite back in the y pipe or do I need to tune or do the 02 sim? Last question is I know everyone likes catman but its 350$ compared to a quick Google search I just did and saw a few y pipes for 150$.

2000 Maxima Warpspeed y-pipe, Megan cat-back - YouTube

This is exactly the sound I dont want. Every time I hear this I picture a prican in a civic. What causes this or better yet what exhaust upgrade can I do to get more power but avoid this sound?

DennisMik

iTrader: (2)

If all you do is replace the y-pipe and eliminate the pre-cats, the sound won't be anything like that video, loudness or tone. That is the result of the Megan muffler. I am using the stock Nissan muffler and it is pretty quiet. I don't know what brand of muffler is loud or quiet. But a muffler that gives you more power will be louder than stock.

I used a Warpspeed y-pipe and it had the bungs (mounting holes) for the O2 sensors. Screwed the O2 sensors in and that was all, no CEL or anything.

maximasicilian123

Can bank 2 precats be gutted while on the car? Gutting this wont throw a code on a 5.5?

JonnyV2889

Anyone know the dimensions for a replacement flex pipe Adjacent to the intermediate pipe? I don't have access to crawl under the thing until this weekend. Hoping to have one waiting for me sat. 01 max w/o egr. Thanks