I'm trying to work out the details for the exhaust system on my '89 with a swapped in 350, and I'm trying to decide whether to go with a 2 1/4" or 2 1/2" system. According to the pipe diameter online calculators I've used 2 1/4" is good to over 400 HP, but people on online forums seem to think bigger is better and claim, without evidence, that if you have a performance car of some sort you should go with a 2 1/2" (or larger) system because you'll always make more power. I personally would trust the charts than people's opinion, and I doubt this car will make more than 400 hp any time soon, so why wouldn't 2 1/4" be adequate? Right now the engine is fairly stock, but I have some better heads and intake to put on it eventually. I'm also looking into one of the 350LT1 spec cams for it. It will have shorty headers and a true dual exhaust, probably with turbo mufflers for a more vintage sound (I don't like the raspy metallic Flowmaster sound).

Any thoughts on this would be appreciated.

 

I forgot to mention that the TBI system was long gone on this car's engine when I got it, so I decided just to keep it carbureted.

 

I have a modified fastburn crate engine, same specs as what is now sold as the ZZ6. My system is true-dual 2.5" pipes with turbo mufflers. Love it.

It's all about what you want, either system will work for your application, you're not going to hurt it by going with the bigger though and that sets you up good for the future.

 

I thought that, too. It's hard for me to judge just how much horsepower I'm going to end up with when do all the things I want to to this engine, though
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I assume you are taking dual vs Single? For anything under 400hp a single 3" is typically enough. Dual 2.5 is good for 400whp or so but is a pain to install and deal with.
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yuuuup. Which is why mine has been in a state of “dump it in front of the axle” for….12 years now? Haha

 

I was just going to try running the pipes out the sides of the car in front of the rear wheels. Isn't that the way the Player's Challenge cars were?