[WarBaby]

Hmmm.. I haven't been getting topic notifications lately but I found this thread "pinned" so...

Warbaby, *absolutely incredible post and info, (once digested). *Here is the question, if you don't mind another. *I put Yoshi rs3 boltons on my busa. *If I understand your info, I paid $550 for looks and a little better sound. *I have been looking for a better 4-2 header, because I like the balanced look of 2 cans. *Any recommendations. *Thanks for your time and knowledge. Peace - Don[/quote]

Thank you.

I did not intend to leave the impression that, for instance, your Yosh bolt-on cans do not produce power gains. Bolt-on cans are fine if that's what one wants but they can't produce the kind of performance gains that well-designed, 4-2-1, 4-1, or 4-2 full systems do when properly mapped. I believe your Yosh cans are of "straight-through" design, unlike the factory cans with their circuitous exit path. That alone should decrease pumping losses and yield some power gains, even unmapped, I dare say.

I also like the balanced appearance of a 4-2 full exhaust system. My personal orientation is simply performance first (4-2-1) and I don't have experience with any 4-2 Busa header systems. A lot of guys rave about their HMF dual can exhausts and I see no reason why HMF (and others) wouldn't make excellent power (again, when properly mapped) as several dyno charts have revealed. Just keep in mind that there is a weight penalty with twin mufflers that must be factored into the performance equation. The single most restrictive aspect of the factory system is the "X" crossover tube which virtually any aftermarket manufacturer could/should easily improve upon.

Perhaps some of the "4 into 2" guys here can give you more specific data about their performance gains.