A tired old question..... and I'm sorry

[Regimof]

I looked in the search function... admittedly I am not forum savy...and found not a lot in the results. Funny thing is I'm sure I've seen it here before.

Anyway. Had the yellow car on a lift the other day looking for anything out of whack and doing a diff fluid swap and I kept looking at the exhaust and the 4 cats....and I'm wondering does it need 4 of em? It seems to me that's an early 90s attempt to please the epa and not much else, especially with the lt5 wanting more flow and all. Do people eliminate just 2? Would it garner any gains? It's got a magnaflow cat back on it now if that makes a difference.

I've been talking to DRM about a few goodies next year and intake and headers seem to be The best first step when spring rules around. So either way it's not staying this way for long.

Sorry again for what I assume to be a repeat question.

[GOLDCYLON]

Originally Posted by Regimof

I looked in the search function... admittedly I am not forum savy...and found not a lot in the results. Funny thing is I'm sure I've seen it here before.

Anyway. Had the yellow car on a lift the other day looking for anything out of whack and doing a diff fluid swap and I kept looking at the exhaust and the 4 cats....and I'm wondering does it need 4 of em? It seems to me that's an early 90s attempt to please the epa and not much else, especially with the lt5 wanting more flow and all. Do people eliminate just 2? Would it garner any gains? It's got a magnaflow cat back on it now if that makes a difference.

I've been talking to DRM about a few goodies next year and intake and headers seem to be The best first step when spring rules around. So either way it's not staying this way for long.



Sorry again for what I assume to be a repeat question.

4 cats ? There are only two cats are the calling the center line resonator at cat? That's for noise cancelation only.

[RussMcB]

As mentioned above, if your exhaust is stock, you should have two cats near the engine going into a single resonator, then two mufflers in back.

I think your future plans to improve the exhaust are good. I don't know of anyone who hasn't been happy afterwards (except sometimes sound/drone is an issue at some RPMs).

Have you seen Marc's information about stock exhaust vs, aftermarket? I think you'll find it under the Articles or Presentations sections on his site: http://www.zr1specialist.com/

[A26B]

On early models, with the cats integrated with manifolds, aftermarket cats were installed by owners downstream of original cats. I have recommended that procedure to customers as a less costly means to pass emissions when the original cats were bad.

Consequently, it looks like 4 cats.

Sent from my iPhone using ZR-1 Net Registry

[Regimof]

Ok. I'm dumb. Not sure what I was thinking.

Has anyone ever cut the resonator itself out and gone straight pipes to the mufflers? maybe add an x pipe to keep back pressure? wouldn't mind more bark, but not looking to be an obnoxious *** either

[Paul Workman]

Lots of Zs w/o cats, w/o resonators, (Stainless Works) X pipes and straight back to mufflers of one type or another. Then there's Corsa cat-back systems many like, ESPECIALLY if drone is an issue (to some more than others). B&B Fusion is their mufflers with the NPP gates some like.

IIRC, Mike 100 is using C6 Z06 cats (3"inlet/outlet), X-pipe and custom NPP with manual control.

Headers, X-pipe w/o resonator, or Corsa and free flowing mufflers are generally good for 25-35+ HP depending on other factors...to give you a rough idea...