Just for what it's worth, 'bout .02, we're talking exhaust flow efficiency.....
The header is specifically designed to keep things moving in one direction. These exhausts that have no muffler on the end are "shaped" to accomodate the lack of a muffler on the end of them, i.e. no back pressure coming from the muffler itself, but "some" provided by the shape and length of the pipes themselves. Back pressure isn't always the result of a muffler. That's not to say they aren't "as" efficient, or "more" efficient at keeping the gases moving that are expelled from the exhaust valves when opened.
The stock header isn't shaped to work that way, as it relies on the mufflers, and the diameter pipe from which it's built to maximize bottom end torque while also allowing the machine to "breathe" at high rpm's and mph. Both muffler design and diameter and shape of the stock pipe is just what it is, a compromise.
You take a Boz, Yosh, Muzzy, HMF, Two Brothers, etc...and they're all designed to extract the gas and keep it moving, by design. Maximize top end flow HP, without totally destroying bottom end torque. Whether there's a heavily baffled muff on the end doesn't really matter as these header's are shaped for efficiency.
Stock pipes are "escape cavities", whereas, tuned exhaust systems are "extraction devices".
After I get this speedohealer issue acquired and installed, I believe a PC will be somewhere in the SpudleyBusa's future. I believe there's better performance available whether I buy a set of very expensive pipes or not. Interested to find out.
Before all that, I've got to get the rest of the two-year maintenance out of the way......got the rear brake flushed and replaced with Dot 4 synthetic, next is the fronts, then the clutch, then the cooling system..........hopefully by tomorrow at this time I'll be all finished...we'll see.
