Onyx Z

iTrader: (3)

Does anyone have any tips on gutting the stock cats.

Thanks
Ryan

TheDogofWar

iTrader: (2)

yeah, don't do it! Sounds like **** IMO.

Seriously though, not really any tips, just bang it on a concrete floor a few times and run a broomstick or something through it. Mkae sure all the catalyst material is out before reinstalling.

ak motorsports

I agree w/ the dog, it does sound like ***; especislly w/ a cutout. i wish i had done hi-flows or an ORP instead of gutting my stockers.

Pat-Man

iTrader: (3)

I'll tell you just like the others have stated above, "Don't do it...it will sounds like poo!" If you want to get rid of them, get some straight pipe welded in there to replace them.

Predator

Just curious, why does it sound crappy? Is it the shape of cat housing, and why does it sound better with an ORP?

RPM WS6

iTrader: (3)

It's actually the oppsite. Gutted stock cats sound much better than an ORY. I have TONS of personal experiance with this as I've tried more exhaust combos on my LS1s than many on this board.

I've had gutted stock cats with:

1) Flowmaster American Thunder catback
2) SLP 2OTL catback

I've also tried an SLP Y-pipe using the stock gutted cats with both of those setups. Sounded the same with SLP or stock Y.

And I've had an ORY with:

1) SLP 2OTL
2) Bassani catback
3) Stock WS6 catback

The stock WS6 catback was with stock manifolds and an ORY and the SLP was tried with both stock manifolds & ORY and with Bassani headers w/ ORY. The Bassani catback was with Bassani headers and ORY only.

I've also had the following with stock manifolds & stock (ungutted) cats:

1) Flowmaster American Thunder
2) Magnaflow catback

So as you can see, I've had a pretty good share of exhaust experiances on LS1s with ORY, gutted cats, and un-gutted stock cats. The result? ALL the ORY setups (including the stock WS6 catback) rasp in the 2100-2300rpm range to some degree, except the Bassani which has a sound more like a deep beating from 2100-2300. BUT, with stock gutted cats and the same catbacks, there is NO rasp. I say that from experiance.

I also have a friend on this board that has tried stock manifolds with gutted cats using both SLP Loudmouth catback and a Random Tech catback, and neither one has rasped on his car either. I'm sure he'll confirm that if he catches this post.

Needless to say, we've all heard SLP Loudmouth with ORYs and it rasps like crazy, but not with stock manifolds & gutted cats.

I don't know where the idea came about that gutted stock cats rasp or sound bad, but it's incorrect. It sounds much better than an ORY with any catback I've tried or heard. Only problem is, there is no way it can flow as good as an ORY.

Predator

Thanks so much for the detailed response! And that's great news to me because I have a Loudmouth and RT cats, but I've been hesitant to gut them because of negative reports on how they sound. I can put that trepidation aside now. If anyone knows how they sound, it's you, with all the experience you've had. Again, thank so much! Much appreciated data.

RPM WS6

iTrader: (3)

No problem!! Always glad to offer experiances.

BUT, keep in mind that I have never used JBA headers or a RT Y-pipe with RT cats. I'm not sure how the RT cat shells in RTs stock style Y-pipe look compared to stock ones, and I'm not sure if using JBA headers would change the sound much if any. I do realize that those haeders are the same lenght as stock with the same collector flange, and that the Y-pipe is a similar design, but again I can't tell you anything 100% for sure with that exact setup as I've never tried or heard it. In theory, it should sound very similar to stock manifolds and cats gutted, but there are variables there.

Just want you to keep those things in mind beofore you go ahead and gut them. The only thing I can say with 100% certainty is that if you were using stock manifolds with stock gutted cats and your SLP LM catback, there would be zero rasp and it would sound great. But with your setup it may be different.

If you decide to try it, let us know what it sounds like. I'm really interested to find out if it is the same as stock manifolds/gutted stock cats.

Predator

I will report the results with my setup. So far, I'm not having a problem with my cats, but I suspect that with COT turned off it's a strong possibility. Anyway, thanks again.

01redws6ta

Gutting your stock cats is a very cost effective way to get better exhaust flow. I gutted mine a couple of months ago. I had to heat up each exhaust manifold stud nut to break them loose without breaking them. Once off, I just used a pry bar to break the inside apart and tipped and shook the converters until all of the contents were out. Then there's a thin layer of insulation around the inside of the shell. Pieces of that were torn up, so I used a long screwdriver to scrape all of that out of there. I reinstalled them with new flange gaskets. You'll probably want to install a set of O2 sensor simulators too.
My exhaust smelled really bad for about an hour after this due to the rest of the tiny pieces of insulation burning out.
I think the exhaust sounds much better now. It has more of a deep tone and absolutely no rasp. The rest of my system is stock manifolds, SLP Y-pipe, stock WS6 intermediate pipe and Flo-pro muffler. It's much cheaper than headers if you're looking to save money (and hassle). Hope this helps!

Predator

01red, did you pick up any ponies after gutting them? Good info!

Smoke_Ford

Thank you RPM WS6, your responses are always in detail. I didn't know you even looked outside the midwestern section...

RPM WS6

iTrader: (3)

LOL!! You think I've made almost 4000 posts in the midwest section alone? Midwest section doesn't even have that many posts to it! :p

I've been away from the board for quite a while now being very busy at home and work, which is why you haven't seen me post for a while.

And, Ryan, as I know you have a Flowmaster catback right now, I'd like to add the fact that I forgot to mention I also had an ORY with my Flowmaster catback. It rasped quite a bit from 2100-2400rpm or so. BUT, with the stock gutted cats and the same Flowmaster catback it sounded great and totally rasp free. Just to let you know...

Smoke_Ford

Well I dont have to worry about it because I spun a bearing so my car will be out of commish for a while. =(

RPM WS6

iTrader: (3)

How'd that happen?? Sorry to hear that Did you at least get some good runs in with the new setup first?

Smoke_Ford

I dont know, I am not even 100% sure that is what it is, but I am 90%. You should hear it. Yo, I need your phone number, for some reason Chris doesnt have it...

Jpr5690

iTrader: (13)

i was told but slp and thunder raceing NOT to gut my cats cause it wont do anything as far as hp goes and you run the risk of not being able to keep stock tunning even with 02 sims. to me im happy with my borla and slp y pipe until i run out warrenty and to long tubes