[BR3W CITY]

Or just run 3" pipe since bench flowing exhausts is still ballparking (just really good ballparking). Most setups wouldn't notice the difference, and since so few of these things stay stock intake/cam/heads you'll end up wanting the 3" anyway.

I'm not discounting your calc, which does offer a lab-ideal result. I just think that even with a program, there are factors that aren't being accounted for. Especially if I were considering a stainless system where cost is a factor, I'd rather build a 3" system I'm less likely to outgrow.