I've read a few technical exhaust articles and it seems like the collector is the most important thing for a nicely tuned exhaust w/headers. I have not seen any formulas for figuring the collector length tho. Anyone have that? I have a '75 350 350 203 33's 4" 12 bolt corp dana 44 with a carter afb sitting on the intake. when i start doing a re-build on a separate 350 core I plan on building for torque and that's the engine I want to design the exhaust for.