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drizzy 07-19-2011 07:01 PM

Cats and Exhaust question
Whats up guys,

I had a straight pipe high flow exhaust and today I took it into the shop to get cats put back on it so I could pass emissions. Well I just got back from picking it up and I was told that putting them back on wouldn't really do anything to the whole car but when driving it back I first noticed it killed my exhaust sound and 2nd I also notice that it took away a very noticeable amount of power in my car. Is there anything I can do without taking the cats off that will make it the way it was again??

Thanks for your help.

mfarnham 07-19-2011 08:55 PM

If you need to have cats, I think all you can do is buy a louder exhaust and get other mods to increase your horsepower.

mines2013 07-19-2011 09:25 PM

Adding back cats will add restriction in airflow out of your exhaust system. This just means not as loud and a little less power like you mentioned. As the person above me said, just look for a louder exhaust and upgrade engine parts for power.

turmic 07-19-2011 09:42 PM

You could get stupid with money and get the steel weeved cats that have less restriction but do a poor job at actually working as a cat. Otherwise, get a louder catback and upgrade other parts.

drizzy 08-04-2011 01:43 PM

Hey guys so they ended up putting a stock one inch cat on which like killed everything. Well the other day they told me they ordered a new one which was a 3 inch high flow one and when i went to take my car today they said it was only a 3 inch universal one which also would throw the check engine light back on. They also said that I would hear knocking and stuff because the guy didnt think it would be big enough which didnt make since to me. Then the guy told me that they didnt make a high flow one for my car and I was like Ive seen them though on the internet. So right now im really confused. Isnt there a 3inch high flow cat that would work for my car and keep the check engine light off?

Thanks again guys.

cwinterbower 08-04-2011 01:52 PM

All kinds of high flow cat's/downpipes out there. Problem is, is it's generally part of the downpipe assembly.
Not sure how it would throw a check engine light on unless you are still running post cat high/lean, which might happen with any high flow cat. Would need to have it tuned out.
No idea on the "hear knocking", that just doesn't make sense.

drizzy 08-04-2011 02:27 PM

yea thats what I thought he made no sense in what he was saying. So should I have the universal one put back on or wait and get a high flow one?

cwinterbower 08-04-2011 03:29 PM

I never run a cat at all by choice (off-road of course ;)). Depends on what you can afford and what you HAVE to have on there. High flow cat 'with a tune' will net you a few more hp as you could tweak timing and boost a bit, if your running the stock dp, it wouldn't make much difference, more sound than anything.
High flow cat + 3" dp is kinda the norm for guys that have to run a cat.

psinuse 08-04-2011 06:39 PM

Emissions suck period. The few options are really expensive, but you can squeeze a bit of power from them, and they don't add "as much" restriction as a stock cat.

turmic 08-04-2011 09:18 PM

Like a Steel woven CAT, over priced for less restriction, but doesn't work as well. sounds like this muffler shop might not be ran by the smartest people out there. If they can't make a universal high flow CAT work then they shouldn't be working on exhaust systems. A normal high flow CAT will work though.

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