Aftermarket Exhaust Necassary?

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Hey guys, I had a question about the benefits of aftermarket exhaust on near stock engines. My 305 TPI gm engine is in stock trim except for cold air induction and dual snorkel k/n's. I know that the 305 doesn't need much more air capacity due to the fact that airflow isn't what's really holding back it's hp numbers, but I was wondering if an aftermarket cat-back system would have any positive effects on torque or hp output in low, mid, and upper rpm ranges? If I tried bolting up a 2.5 inch, non-chambered muffler, single cat setup like a Hooker cat-back, do you think that it would be beneficial to my engine? The reason I do ask this is because I need to know where my money is best spent. Maybe a higher duration cam and lifters would be better money spent for mid range torque and upper rpm hp? Thanks for any help you all may provide me with.
-Rob

posted by  Rob88Z28

It will give you more horsepower but with a 305 you dont really need it unless you a race the car

posted by  archangle

If you remove the catalytic converter you will increase the flow by quite a bit, it wont really mean an excessive power increase though :thumbs:

posted by  Cliffy

in the states if one removes a catalytic converter the car is undrivable as far as i know...won't pass emissions

posted by  SuperJew

It wont pass emissions here either, and it's far from legal, but it's perfectly drivable lol :hi:

posted by  Cliffy

I don't think I can remove the cat because the emmisions in california are pretty tight, so I think I just want to put on a cat-back system. I do plan to take to the track sometime to try and get a low 15 out of it, but if i could better get more power for less money elsewhere, then I would rather do that.

posted by  Rob88Z28

Why not put a straight through pipe on it when you want to race it, that's the only way you're going to significantly increase power, even then it wont be exceptional lol...or you could use it for every day use, just remember to put the cat back when you have to have the car inspected...Do you guys in the US have a yearly check that has to be carried out?

posted by  Cliffy

I could put a straight piping in but i don't want to hurt torque or backpressure to much, and its not a racer, i just want to take it to the track just a few times, nothing extreme. We do have inspections when getting it smogged so if i did that i definetly would have to put the stock setup back on there though.

posted by  Rob88Z28

Also, if you decide to put on a straight-through pipe, you'll have to watch how hard you push your engine in heavily-policed areas. The stricter cops will ticket you for noise pollution... :banghead:

posted by  Patrick

It shouldn't be much louder without a cat though....cats dont usually deaden sound much, it's the centre silencer you've gotta be carefull of

posted by  Cliffy

True. I was just saying- someone I am vaguely accquainted with just got a ticket for noise pollution, and he recently had his cat removed... but the cops around here live to make teenagers' lives a living hell, too. So I don't know. Since I have no idea about California laws and the ego size of the cops there, you may want to disregard my former comment.

posted by  Patrick

I guess different States vary quite a bit, in the UK, Cops dont really tend to bother with noise pollution, unless it's excessive :laughing:

posted by  Cliffy

a Cat-Back system will help your motor breathe better and it will be required if you plan on adding a cam/intake setup later.

posted by  HotrodTSi

but since the motor isn't modified, could money best be spent elsewhere for better torque/hp gains? or would a 2.5 inch cat-back actually help a stock 305 tpi breath better?

posted by  Rob88Z28

intake/exhaust w/ f/i helps quite a bit, so save up.

posted by  importluva

I was reading this discussion and I have a question. If you hollow out a catalytic converter on a 96 GMC Sonoma, will the performance be affected? Will it cause any problems, besides emissions?

posted by  stonefacedgirl

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