cat or no cat


Asked by Feb 18, 2009 at 11:15 PM about the 1991 Chevrolet Camaro

Question type: Car Customization

i have a 1991 camaro rs 305 with a flowmaster muffler and i am thinking about removing the catyletic converter for a little more sound. what do you guys think?

11 Answers


Less restriction more flow=more horse power and better sound....buuuuuut,only if you are willing to pay the fine if ya get caught bro


ditch the stock cat and spend a little extra money on a high flow dynomax cat. they are around $300-$400 which i know sounds like a lot but they will keep your car street legal and they sound great too. i had an 87 without a cat because i thought it might be the way to go but when i got my 89 i went with a full dynomax exhaust including cat and it sounded much better than my 87 with just a muffler(flowmaster)


thanks for the info, but i indiana where i live, the cops are only concerned with the car being to loud. there are no emissions testing here. i was just thinking about removing the cat and putting a test pipe in its place, i have heard other camaros with this done and it sounds amazing. also, i have a small exhaust leak in front of the cat due to shotty welding.


yeah i understand there is no emission testing but if some cop is being a prick one day and decides to check your exhaust cause he notices that its louder than stock and there is no cat its a big fine. i understand if you dont go with the cat though as i did it once also.


if you want to work around it you could just hollow out ur cat. so if they do look under your car there will be a cat there, but its just hollow. same as taking it out but the look of it there =)


haha, i like that idea, but if i take it off i will probably sell it. Cats are going for big bucks right now, especially the older ones, they have platinum in them.


yea good point but if u hollow it out you can still sell the stuff inside from some money... may get more with it all together... and if you about it you can save your self a big fine if you get pulled over and dont have a cat. things to think about.

ditch the cat..if they dont do emissions or state inspections where you live you dont have to worry about it


dont forget that with too little of back pressure from the exhaust that your exhaust valves will also burn up and you will lose some low end power. remember im the one who went without a cat and then had a high performance one on a full system and i suggest the full system with a cat instead of without


Along with what Chase is saying, you should remember that if you reduce back pressure too much you will actually be removing good air and fuel out of the combustion chamber which could result in detonation when pushed. Engines with cats are usually camed to take advantage of the cat and allow for as much exhaust removal as possible with the cat in place. I would recommend getting a hig flow cat, that way you have a faster flowing exhaust yet retain enough backpressure to reduce/eliminate detonation.


bad for the flow thorugh and you may not ever pass inspection again lol

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