I did the Yosh slip on's as well, and overall while the sound is good, it does seem a little lacking for what I would consider performance at lower horses. I even have received an occational backfire on a quick throttle off. Also, my mileage (he he he --- on hard throttle as if there were any other position) is quite a bit lower. I am considering doing the pair mod.
considering it... like Nike says... Just Do It. (the marble mod)
ya, the lower rpm range suffers.
ya, milage suffers.
All them engineers, sittin' around day, after day,after day, eatin stale rice...
whadda think they were doin'....
THEY WEREN'T building a bike that someone else would have to tune for them... to try and get 4 extra horsepower...
I know...I'm in the minority... I just like my bike to have reasonable HP (recently dyno'd @ 156,198mph) to have drivability, to get decent milage....