cwmoss

I bought a 1989 IROC 5.7/auto and it doesn't have a cat, just a "filler". There are no lights on the dash. It has a Flowmaster cat-back system which I am going to take off and replace with a Dynomax cat-back to get it a little quieter. Should I get a new catalytic converter to go with the new system, or will I be ok running it without a cat? It runs very well now, just a bit loud for me.

sofakingdom

iTrader: (1)

Try the new exhaust and see. Basically just look at the ends where stuff bolts up.

Hopefully when they hacked the cat off, they did it in such a way that everything stock still bolts back up. That way, you can always just buy the right cat and re-install it, if you need/want it for whatever reason.

brianlibby791

You will be perfectly fine running without a cat, doesn't cause any issues with the running of the engine. Do you have historic plates on it or no? If you do you can take the fake ones out and just have a straight pipe put in to loose some weight if you want. If you have regular plates and need to go to inspection then leave the fake ones in so when they look for them they see them and dont fail you at inspection. I dont have the cats on mine, just straight piped to the muffler and i have had no issues yet, runs great.

cwmoss

Thanks for the replies. I do have Antique Plates on it so I do not have to get it inspected as long as they are on it. I'll just leave it as is (no cat), I just didn't know if would throw a code not having a cat in the mix.

sofakingdom

iTrader: (1)

No codes... our cars don't have a 2nd O2 sensor downstream of it to measure its efficiency or lack thereof, like newer cars do.

cwmoss

Thank you. I was wondering about that.