Best flowing exhaust manifolds

jon, the key thing is to remember what the purpose the manifold will serve. Like gettn said you can cut them thin for race application, but those parts are changed every season.

For street use you want to go no lower than about 3/8". THis gives you plenty of meat for structural rigidity and still gives you more room for exhaust gases to flow through.

Jake  

More metal removed is not always a good thing. The main thing to remember when porting is you dont want to remove any more material than is needed. Dont get me wrong since your playing with leftovers by all means play until your heart is content. This is all part of the learning curve. I practiced porting on cracked chevy heads cause you dont want to screw up a good head! lol  

I was looking through my exhaust manifolds and found i have two types. One type is the short compact design that i pulled of a 305 out of a mid 80's chevy 2wd truck and the other style is like what comes on factory 350 78-81 camaros. The truck style is shorter but looks like it has larger tubes. The camaro style have long primaries that dump into a slightly larger collector tube but still is smaller than the truck style. The larger chambered would prolly flow better but im not positive. Am i on the right track?  

Of the two the truck style would be better so practice on the camaros. lol