i'm waiting for Ben to reply, because I think the 3400 heads outflow the 3500 heads when they are race/boost ported, and I know that the 3500 UIM outflows the 3400 UIM.....

Yes you have it right. Race/Boost ported 3400 heads, race/boost ported 3400 lower, race/boost ported 3500 upper. The 3500 heads and lower are best if you don't go with my race/boost ported stuff.

sweet, oh i'm gonna be hacking off the end of a 3500 UIM and welding some pipe on their with an attachment plate for the northstar TB, I'm assuming I should do this first, and then send it to you for porting and flow testing, in case my piping messes with stuff?