Exhaust System

Moy

Moy

It's broken...
Aug 6, 2008
2,432
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36
Beach Park, IL
I have an '88 that came from California. I know that there is a pre-cat built into the DP. I need to know if the regular cat is welded or bolted on, for one.

Another thing is: will getting a non-cat DP help my HP and/or throttle-response any?

I understand that some of that might be a little confusing, for that I apologize.

Thanks for your help
 
CRE

CRE

7M-GE + MAFT Pro + T = :D
Oct 24, 2005
3,485
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Denver, CO
It'll help... but if they're not clogged it's nothing you're going to really notice. If it were me I would convert it to non-CA specs and if the cat is shot I'd invest in a good high flow cat to replace it.

You will never notice the difference in performance between a test pipe and a healthy cat on a N/A.

EDIT: I should add that the CA model MKIII's are not slugs. Yeah, I've only ever seen a couple other cars where the CA modifications turned them into a complete slug. Not the MKIII. You could ask SupraRX7Nut about his. It's still CA spec and he lives here in CO (high altitude). His car probably does better than most of the N/A's I've seen around here. I'd ask him because he's driven so many before buying that one so he could probably give you a decent point of view.
 
suprarx7nut

suprarx7nut

YotaMD.com author
Nov 10, 2006
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Arizona
www.supramania.com
I've been debating attempting to rid my car of it's Cali-spec crap, but I'm not very sure of the performance benefits. Like CRE said I've driven quite a few N/A's, both cali and not and I can't say I noticed a difference either way.

The cat in the front part of the exhaust on a mkIII is welded into the piping on every car I've seen, unlike the 2nd cat, which should be flanged.

If I end up doing exhaust on the N/A I will remove the first cat by replacing the front pipe(downpipe, i guess) with a non-cali N/A from a junkyard and then do 2.5" the whole way back with a good muffler and resonator. Although I'm not sure if removing the first cat will do anything without also swapping the ECU for a non-cali.

I really wish there was more info available on the differences between the cali and non-cali N/A's...
 
Moy

Moy

It's broken...
Aug 6, 2008
2,432
0
36
Beach Park, IL
About the DP thing, I didn't really know the difference, so I apologize for that, I just assumed DP because it's a pipe that goes down from the header to the cat. Oh well, people make mistakes, right?

If I replaced this pipe with a non-cali spec pipe, would I need a non-cali spec ecu or could I run it on the cali ecu?
 
suprarx7nut

suprarx7nut

YotaMD.com author
Nov 10, 2006
3,811
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Arizona
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Jervis Mcstabby;1117599 said:
I cut mine a while ago, because the muffler had cracks under pipe tips, I'm pretty sure I'm using the the same ecu (I'll have to check though).
Click to expand...

You cut your front exhaust pipe(directly under the manifold) because your muffler was cracked? I'm very confused. Not sure we are on the same page here...
 
Rennat

Rennat

5psi...? haha
Dec 6, 2005
2,844
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Tracy, CA
www.myspace.com
FWIW.... i had a test pipe on my car, it was throaty and had the 'rifleing sound under throttle...

put my 'stock' cat back on, ALL of that was gone, and i couldnt pass smog.

get a new cat, and my rifleing sound is BACK!!!! omg wtf!?! no way right? no, its because it wasnt CLOGGED full of shit.

point in case, a good cat is just as good as a test pipe. /thread
 
Moy

Moy

It's broken...
Aug 6, 2008
2,432
0
36
Beach Park, IL
I don't want to go OEM for replacing the pipe because I don't really want 2 cats on my car. Cheap is fine as long as it does its job and doesn't leak.
 
chedderknight

chedderknight

PiYauD-BaKa
Apr 4, 2005
366
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Glendale, CA
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Has anyone here Cut and welded a new pipe under the manifold that leads to the cat? i have a non-cali spec MKIII, and the gaskets there keep blowing out, makes for a really annoying exhaust leak, would a general muffler shop handle something like that?
 
I

Island_Yota

New Member
Aug 5, 2008
264
0
0
Vancouver Island
I picked up a used Pacesetter Cat-back system with a 3" test pipe, lots of top end power where it didn't have it before but its lacking in the lower rpm's now. Im going to try it with my Cat, its in good shape. Il take some video to see if it changes the exhaust note at all.
 
I

Island_Yota

New Member
Aug 5, 2008
264
0
0
Vancouver Island
Ok I listened to the rumors about Cat-Deletes or "test pipes" on N/A's and everyone who says its a bad idea is right. I had a 3" Stainless test pipe with the Pacesetter catback system, I put my Catalytic converter back in today and it sounds much nicer. The back pressure helps alot, or whatever is going on.. the cat is in good shape its an OEM style no carbon buildup at all its been replaced before. My butt dyno shows that I got my lower RPM torque back for the most part but lost a bit of top end power, fine by me I like being able to pull from 80km/h to 140km/h in 5th gear like nothing.

The exhaust still drones at certain rpm's but its alot quieter and im pretty happy with it now.
 
Rennat

Rennat

5psi...? haha
Dec 6, 2005
2,844
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0
Tracy, CA
www.myspace.com
my cat was just a regular replacement from an exhaust shop... nothing really 'high flow' about it... it was just not clogged. hahaha

it passed smog for me, so i was happy.
 
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