Stock Cat Mod
 

Ok, so I am going to ask the question... On the 370z the stock cats have two cells...one which is monitored buy the a/f sensor and rear 02 sensor..after that there is a cell I would refer to as a clean up cell... has anyone removed this? any gains noticed? obviously u would not get a MIL cause its not monitored.. just curious... the main stock cell is small in size and I feel if u removed the secondary non monitored cell it would probably be equivalent to a high flow cat? ... this is just theory..if anyone has tried this, please let me know.
Thanks Tim

Wow that's a good question. It sounds right but I have no clue. Definitely interested in responses

the outlet diameter is still very small i believe. so not sure what you'd gain.

A lot of other car enthusiasts gut their cats. Probably won't be as big of a gain compared to test pipes, but definitely a power gain.

Thanks for the response. I don't really want to gut the whole cat...just the second cell...a few collogues and myself was looking to do that on my car before installing the cat back system...but I got cold feet...not sure if it would sound bad, ect... I am sure someone has done this "mod" it looks fairly easy..again, didn't want any drone or rasp and such.
Thanks,
Tim

Heads---->stock exhaust manifolds--->AFR sensors--->cats---->rear 02 sensors---->muffler

so removing part of the cat will throw a code because the rear 02 will think the cat is damaged

Not sure how you are going to remove just part of the cat either without tearing the whole thing up...and for little to zero gain. Just get test pipes and a tune

The stock cat has a separate 2nd cell AFTER the rear o2 sensor that is not monitored. That's what I am questioning to remove...if it was monitored it would have 3 sensors per back if that makes sense..

I had to go back and look at some pictures. I see what you are talking about. And yes that "second cell" would not be monitored by the rear 02.

But IMHO there can't be much to gain here.

Thank you for the response. Yeah I am not sure either how restricting it is....there is some...but 1-5 hp ? probably not worth the effort...lol.. thanks man.

It's a nice idea, but you'd probably be better off getting HFC's or TP's.

I guess if you can get to them easily enough, and can do the work yourself, no harm in experimenting, but those cats are a real pain to break loose -- search for "demon bolts"...

EDIT: Actually, come to think of it, are you sure that's not just a resonator you're referring to -- I've seen several sets of cats off the car, and I didn't think there was more cat after the O2 bung :confused:

It very well could be some sort of resonator, it didn't even think of that....its hard to tell cause it looks similar to a cat cell....but I agree with u...not worth the effort and probably is a resonator..
Thanks for all the feedback!