Alright guys, I'm at a bit of a crossroads here, sort of. I drive a '91 z28, 305 TPI. I've been doing a lot of reading and research, and can't find a real 'straight' answer to the question of which style headers to go for, long tubes or shorty.

Both would be 1 5/8", and from my understanding, long tubes will make better low end, and shorties will have better mid-high? Is that correct, or even close to it?

Continuing off of that, I also came across a lot of forums/posts/articles that said exhaust pipe diameter plays a huge role as well, though, again, people are on the fence about whether large or small diameter pipes are the 'best'(yes, I know there is no real 'best,' unfortunately). I do have plans for this engine (heads/cam) but I'm starting with suspension, exhaust, opening up the intake manifold and such, first. Would 2" exhaust, or 2.5" exhaust be a 'good' size? The heads/cam won't come for awhile, probably not until late this summer, so would one be better than the other until then?


One final question, though just one out of curiosity, how important is a muffler? I plan to run one, not sure on which one yet, but I've always wondered how important having a muffler is. Does the backpressure have that much of an effect on the efficiency of the exhaust?

I'm sorry to beat the proverbial dead horse with these questions, but I've just not been able to find anything concrete enough, as it were, and, honestly, as much as people argue about it, I'm a bit more confused than when I started haha.

 

Even with great heads, as long as you run a TPI 305, the theoretical best header would be 1.5" long tubes. These can support about 440 horses before 1.625" shows any advantage. The TPI intake manifold design dictates your engine's useful rpm range. For the cat-back, a good 2.5" single will support 270 horses without restriction. Dynomax has a good 2.5" cat-back, but the muffler they include isn't good past 200 horses.