I will be running a blown 496 in my '74 k20. Its a little 177 cu in. Holley blower, with a ported 850 cfm Holley double pumper custom built by AED for my motor. It has an Isky 270/280 Megacam just like whats listed, but with a 112 degree LSA: http://www.iskycams.com/productdisp...c=101&dealer=no It should make 600 + hp/tq and rev to 5000 rpm maximum. It has a 700r4 tranny / np 208 t-case I currently have 1.75" primary Hooker Comp headers with a single 3" tailpipe, and was considering going with 2" primary Supercomps and a dual 3" exhaust. I want to build good low end torque without choking the motor (hence the small charger and relatively small cam for a blown 496). The first header listed is for a '68 + Chevelle/Camaro. I was hoping to avoid the low hanging, shackle interfering truck header problems. The second headers listed are for a truck, and also don't have equal legnth primaries... http://store.summitracing.com/defau...earchinresults=false&N=0&target=egnsearch.asp http://store.summitracing.com/defau...sults=false&N=0&target=egnsearch.asp&x=42&y=9 Also, I will be building the exhaust myself, so I was thinking a 3" dual dumping in front of the rear wheels will be easy, a single with a 4" or so tailpipe will be more work, plus 4" exhaust pipe is expensive. I did a 2.5" dual on my Burb and only needed (2) 180* mandrel bends for the whole thing. Please offer any recommendations on the planned exhaust system. I am open to any changes in parts / design you may have, but please support your opinion with some reasoning. I am also interested to hear how the fit is on the Supercomp headers, and if you think the car/truck/other model headers will be the best fit. My current Hooker Comp truck headers fit GREAT, so I am thinking maybe the truck model Supercomps are the way to go... Or, do you think my current exhaust system is adequate, or will it be badly choking my motor?