In my eyes the 3" collector would be to big, i would rather have 1 7/8 primarys, 2 inch secondarys, 2.5 inch collector, 3 inch exhaust. as it would be eaiser to keep the velocity up by slowly increasing the pipe size.
But what do i know, my cars slow.
Not saying that at all. Sounds like a good header design. I do disagree about h2b. h-series have a 18 percent drivetrain loss, long gear ratios (4.2 final), and poor axle angles. However, B-series trannys have only 12 percent drivetrain loss, better axle angles, and much better gear ratios.