2" or 2 1/4" 327 exhaust? need help/opinions...

[chewychevy67]

I agree with that but I wonder why pretty much all the turbo mufflers I have looked at downsize quite a bit inside the muffler. Seems useless to have big pipes when the choke point is the muffler.

[p0508]

If whatever muffler you buy is...

1. Not straight through
2. Downsizes inside

It is cheap and you are paying for a restriction or comfort.

[siggyfreud]

Originally Posted by Beat68CST

True 2" is plenty fine, it will have more low end too.

If you want more sound and close to the same performance, 2 1/4".

Don't go 2 1/2 on a stock SBC, they need some back pressure.

Back pressure is always bad. What exhausts need, and what you can lose by going too big, is scavenging, which helps keep exhaust velocity high. Back pressure would mean that exhaust is moving out of the system slower than it could, which is a bad thing. You want maximum exhaust velocity, as air out allows air in, which is the whole point of the engine.

People often conflate back pressure and scavenging, but they're two different things. One is bad for performance, one is good.

[Steeveedee]

Originally Posted by chewychevy67

That would be great. It's funny that you had a 64 because the mufflers I have are left and right 327 300hp mufflers for 64 passenger except wagons. . I just went out and checked and the I'd of the exits are just a hare shy of 2". How did the car sound?

Right after I put the whole exhaust system on, before it got all carboned up, I went to the Chevy dealer to get some other parts. Every mechanic at the parts counter turned around to listen to the cack. Of course, once it got a layer of carbon, it got a bit quieter.