305 header size ???

[MEXJOE]

Originally Posted by Alan Nyhus

A correctly done tri-y will make more torque and still run up high. It may not show as big a h.p. number on the dyno but may very well go down the track quicker. If you're willing to go further, cam changes can find more power and torque, depending on where you're at now with the cam numbers. Think of the tri-y's as a stepping stone because they are are also a considerable investment. Needless to say, we're talking about a really good set of stainless tri-y's here...something from Cal Elston, Performance Welding or someone that understands exhaust port dynamics, not a set of ebay special tri-y's.

Just my experience with them, FWIW.

For a conventional 4-1 header, I'd happily pick up the phone and order a set of 1 5/8" and go racing:

https://acpheaders.com/

Ben Line is a real craftsman and makes great headers:

https://www.headersbyben.com/

Ben is very good!