Like everyone else I am tired of waiting on headers to be made. So in the meantime I took matters into my own hands. I got these from a junkyard.




Rear Manifold


Rear Precat



Rear Precat


Front Precat

 

Front Manifold





Cat Gutting Tool




Gutted Front Cat

 

I did a mild port on the exhaust manifolds to open them up a bit. I'll get more pictures of them later. There was definately room for improvement on them.

 

The rear precat was a big PITA to open up because it has steel mesh inside. I opened up the exit port to allow more flow.

 

Not bad, damn they are rusted fairly well. How much of that crap is on your hands?

 

Can't wait to see the results of this. Good luck with the project.

BTW I believe the 350Z guys have "straight pipes" to replace the precats. This looks like it could be an option for us since the precats are can be seperated from the rest of the exhaust system. Is this what you have in mind if gutting the precats yield results?

 

But the people with the 350z, if they are replacing the precats with straight pipes, they have to be getting SES light and O2 sensor codes for missing cats. Only way to frig that is using an O2 simulator.

Dixit

 

nice work Matt!!!


if it isnt too difficult, you might consider putting some piping inside of the cats, It'll help keep the rattling noise to a minimum.


(I thought you were going to try to use that drill bit to port them.)

 

I'm not sure if they are getting the SES light, I'll go back and read the threads again. Even if it did, couldn't we get around it by putting the o2 sensors behind the main cat?

 

Yeap that is what I had to do for my turbo setup, since we removed all the recats, I had to relocate them behind the main cat. But thats not just a plug and play job, need to weld two bungs back there now. But now the main thing is that I cant remove the main cat. Which I want to.

Dixit

 

Oh yeah, the Roto Zip is piece of crap. Don't ever buy one. I would recommend the dewalt rotory tool with the 1/4 shank which is probably better than the big dremel (1/4" shank).

Dixit: I had a huge mess when I finished porting the manifolds. I was covered in shards of iron. I was wearing eye protection but a whole face mask would have been better. It took awhile to vacuum all the crap off the driveway.

03BlkSETE: I hope to get some gains but the real benefit should be on the bottle where I need all of the exhaust flow I can get.

 

there we go, someone disecting and gutting
good sh|t matt, keep us posted.

 

When all else fails, either go ghetto/redneck style.....

 

Thats what I did with my 01, the front part the the y-pipe I could not use, so I gutted the cat

 

Keep it coming Matt.

 

Got pics?


I am suprised the pre-cat came off, mine is stuck together like no other.


What's up Dixit

 

the front manifold looks rediculously restrictive.
Are you planning at do dyno after this matt?

 

The cali spec 99 Maximas have 4 O2 sensors in the Y pipe to check and make sure that the precats are still there. I presume that all the newer Maximas are as strict or maybe even more so. Won't you get a CEL with this setup?

DW

 

 

Ok this crap is finally installed. It took me about 7 hours to do and my arms are raw hamburger now. I know what you went through Ethan. That rear manifold is a serious b!tch to remove. Damn Nissan and their worthless razorblade heatshilds.

The butt dyno doesn't really say if the car is quicker now and I can't really tell if it's revving through the gears any quicker. But I did immediately notice that the motor seems quieter and smoother up top than it was before. When I first installed my Y pipe I hated the way the car sounded and felt. Now it's almost as smooth as stock.

 

DId you ever end up porting the front manifold out a bit?
THat looked very resrictive...

Im going through the same thing as u with the Y, i want to take it off.. but well see.. DId the car pull an SES ?

Are you planning to dyno to see if flow is actually better?

 

Notice above where i mentioned I was covered in piles of metal shards. Yes I ported just about everything but I could have done more.


And no SES!!


I just hope it stays that way.

 

Weird how my idle also smoothed out a ton after removing one of my pre-cats.

 

you still have the stock muffler on matt?

 

yeap

 

Hell yeah

 

haha
that would be nice and loud

lol
a loud fart civic just drove by
why do they put mufflers on if they know it sounds like sh|t? hahaha

 

hey SR, so you couldnt feel any acceleration difference? Maybe if you have time you could try it at the track.

 

My butt dyno has been to the Humblemaker too many times to make guesses. So untill I go to the real dyno I gained Zero power.

 

dyno
dyno
dyno

 

+ -3 whp

 

 

If I wasn't such a tard I would do this project also. If I tried I would cut my arm off

 

Well crappolla!!!


P0430 Generic Catalyst System Efficiency Below Threshold (Bank 2)

 

uh oh
gonna have to live with the code

 

dod u feel any improvements? my front precat is breaking away or some **** so i figure i might as wel knock it out till the stillen header y pipe combo comes out!

will

 

Put some black tape on the dash to hide the yellow light

DW

 

I cleared it and tonight the thing came back on.

 

Like I said, I did the same thing with mine (well one part anyway ) and ive had the code for a long time now. Its takes a little while for it to come on the 1st time, but after that no matter how many times you clear it, it comes back within a few min of driving. You'll get used to it...unfourtunetly

 

There is a fix and I willl find it.
And you are right, I drove this thing for a week before the light came on. Now it comes on within a few mins of driving as you say.