I ran a big roller cammed 13.5:1 406 with $300 set of 1-3/4 Hooker Super Comps with a 3" flowmaster exhaust w/crossover (no tailpipes). I used to shift at 7000-7200 and the 3500lb car ran 10.4 @ 128 and 9.5 on a 200 shot. I wasted $1200 on a set of Lemons 2" big tube headers and the car didn't pick up squat...Not worth the $$$ IMHO.