gotta go 3 inch

You would think if you were going thru' the trouble to generate a guideline chart, that
you'd at least get the math right. The 3" pipe listed at 7.1in.sq. is totally wrong,it is MAX
6.492in.sq. if it is .062 wall tubing, less if it is .043 wall tubing. I've seen that error made
over & over, amazing, go 3" and you won't be sorry...from experience.
Go to Burns exhaust site, they give it to you straight, esp. regarding exh sytem length.

Oh yeah, the 462" Olds I built for a friend is running 3.5" all the way out back.