88GT_5.0Stangman

ok im gonna be gitting bbk long tube headers with 2.5 in collectors because they dont make headers with 3 in collectors, and that is what my h pipe is. heres the ? should i get the bbk 2.5 H pipe to match the headers or have my 3 in H cut and welded to except the bbk headers? also 3 in may just be to big anywho. one more thing shoud i get 1 5/8 or 1 3/4 headers? right now i got 1 5/8 long tubes. my set up by next year will be 347 stroker afr 185 heads custom cam...ect all that good stuff and a 150 shot

1985stang

general rule of thumb. 3 inch is for 400 hp+. Under 400 and you'll lose low end power. i don't know about your header questions.