This info applies to a 95-99 fed spec y-pipe. Others are probably the same.

After tearing apart a few stock y-pipes to recycle the cats I got to thinking.

Everybody says the power from an aftermarket y-pipe comes from removing the restrictive pre-cats. The pre cats to me look exactly like the main cat which everybody says is not restrictive. So how are the pre-cats restrictive?

The stock flex section is composed of an outer braided layer that you can see,a metal layer and an inner braided layer. Sorry for my terminology. There are pictures in the link below. The inner braided layer is suppose to be 2.1" OD. On every y-pipe I have dismantled this inner layer was collapsed and was only 1.5" OD. So maybe this is the restrictive part in a stock y-pipe along with the indentations from the o2 bung and on the opposite side of it.

I'm going to measure the size of the pipes later today and add that info.
The entire pipe before the flex section is around 1.86"- 1.90" ID and stays about the same after the flex.
I also measured my warpspeed y-pipe and it is 1.90" - 1.99" ID but after the flex it goes to 2.30" ID

Pictures show metal layer and inner braided layer of flex section and y-pipe without any heat shielding or flex section.
http://s235.photobucket.com/albums/e...ckford/Y-pipe/

 

I like this thread.

Some time this summer I will have an equal length Y made.

Subbing...

 

I want to see pics of the original equal length stillen y pipes!

 

I like this thread too...................in the 4th gen section. Moved.

 

Pulled my stocker out of the box-o-parts laying around and had a look tonight. Let's hear impressions (possibly numbers...) with one of these modified stock pipes installed.

I'm not huge on the o2 sensor mount design and the merge but have been planning an equal length pipe so this may be an quick project.

 

Can someone clarify for me what an equal length y-pipe is? I have been seeing that term more and more in threads...but back when I was getting my pipes (I ended up getting rid of my SS AutoChrome pipe and getting a Fed. Spec (I'm Cali) instead) it wasn't 'around'?

 

go to the cattman group deal and you can see pics.
The length of pipe from the headers to the collect are equal lengths. The rear header side (closest to the firewall), the y pipe pipe bends around in a loop so it is just as long as the front one. Im not sure of the power increase but it is suppose to sound alot better.

that is not at all what my stock y pipe looked like (95 fed spec btw)

 

Thank you. If it's just sound for the most part that benefits from this, no biggie. I like the sound of my car as it is. I'm not into performance that much anyway.

I have SS AutoChrome Headers, Fed. Spec Y-Pipe, Magnaflow High-Flow Cat, Budget B-Pipe, and OEM 4th Gen Muffler and I love how the car sounds.

I need to shoot some drive by videos and post them. Maybe I'll do it this weekend if the weather is nice.

 

http://forums.maxima.org/showthread....ight=y+stillen

 

IIRC, Mine was nothing like that either. Are you sure that's a Nissan OEM y-pipe? Aren't there companies that make stock y-pipes? (walker, bosal, dorman, etc?)

 

verry interesting. I may be making my own when i get around to it in that case..they sell J bends on summit and stuff.

 

I'm sure it's an oem y-pipe. I have cut up 5 of them in the last few weeks. The one pictured looks different because there is no heat shielding.

 

Gotcha. That totally makes sense now that I think about it. I can't believe how tiny it is inside the stock flex!

What about the fact that the rear of the stock pipe almost flows against the front? Maybe the aftermarket pipes are also better because they flow in the same direction where they join?

 

I think if we were to add a different flex section and larger pipe after that and before the cat we could see some gains. I'm not sure how much since we still have the restrictive o2 indentations.

 

Yea but you still have the issue of the pre-cats, plus you don't really wanna have that mix of old and new pipe welds at the second hottest section of the exhaust

It does kinda suck though that the sound I have now is basically what I'll get w/the equal length. The sound is in the headers. Still gonna go custom equal length though.

 

fanaticrockford, are you planning on putting a decent flex on one of the OEM pipes and fitting it on the car? I would be very interested if anybody tried this as I would rather not hack up my Warpspeed to do an EL design. I really don't like the merge from the rear bank though on the stock pipe where the gas hits a wall and then makes a 90 degree turn.

Has anyone modified a non-EL y-pipe to equal length? Do you simply take measurements from the front pipe and then make a loop on the rear? I may run by an exhaust shop this weekend to get their thoughts/pricing. If I had a welder this would be done like yesterday.

 

I'm sorry but the stock pipe looks like it is equal length...

 

Problem with the stock is that it does not have a good Y connection. It has a T



And this is what the stock ypipe looks like with the coverings.


And the stock is equal length. I would love to have an equal length ypipe because I believe that is one of the major reasons for the raspy drone 4th gens get with an aftermarket ypipe/muffler

 

so there is basically no way to get equal length without adding a loop? I think I'm going to get some of those longer tube headers off ebay like someone else mentioned and then make a y pipe off of those.

 

I'm really not confident in any flex section right now. After looking at the stock y and comparing it to my warpspeed y it also has a crushed flex. My warpspeed y is a little over 4 years old but only has about 5000 miles on it. Dallas has offered to replace the flex for me if I send the pipe in so great customer service.
http://s235.photobucket.com/albums/e...ord/warpspeed/

 

Why do they line the inside with the steel braid? Because on my Y-pipe I need to get a new one because the outside steel braid is rusted off.
What would happen if you didn't have the inside steel braid? Wouldn't it fix the problem?

 

Warpspeed had a version without a braided flex section at one point. Would it put stress on the headers to eliminate the flex?

 

It is. That's kind of what the discussion has been about.

 

I would think so...but then again I've seen cars (like my friends stang) without them, Although, that is RWD...so it's maybe not the best comparison. I bet you could get by without a flex section if you had eurethane motor mounts and exhaust hangers.


PS: are you nocturnal?!

 

Here is a 3ply flex sextion. Works fine.

 

I actually have filled mounts and use stock style hangers with an ES bushing pressed in the middle and then hose clamped firm.

If I knew the condition of my flex to be similar (as in collapsed) I would cut it out with a quickness. My pipe has looked the same for 3 years so there is certainly no exterior evidence of this situation.

And yes, at times.

 

I would be interested to see what others do look like.
My pipe showed no evidence as well.
I remember reading of someone else having the same problem with his warpspeed y-pipe.
Here it is and there is more then one person with the problem.
http://forums.maxima.org/showthread....psed+warpspeed

The weird thing is I ran a 13.8 with my warpspeed so maybe it wasn't collapsed then. I drove the car once after that day and it has been sitting on a shelf unused ever since.

 

I've got an old warpspeed, but it's on someones car. Once I get it off, I'll take pics of the flex section. It's barely two years old so I'm curious if it is crushed or not...