I'm thinking that every combo is different. Take collector extensions, and maybe some bigger jets. Try to baseline w/ exhaust, then open it, using 18" extensions.
If 100 lbs. is a tenth, that weight has to be worth 5 hundreths.
I agree, each car is different and at higher RPM's tail pipes and mufflers can take some away.
Also, cut outs and dumps don't help much because the exhaust doesn't have a straight shot out the pipe. The only way they work is if you set it up where the exhaust goes out the collector and strait through the cut outs about 18" from the header with out any obstructions or bends and have your exhaust pipe come off the side of it just before the cut out and curve back from there. But you still have the weight of the exhaust and cut outs.
