Well, I installed the Yosh RS-3 slip-ons today. Instllation was pretty straightforward... till I went to install the exhaust gasket at the pipe joint, anyway. That's when I noticed the gaskets wouldn't fit into the slip-on's inlet pipes. It seems that Yoshi designed the slip-ons to attach without the gaskets. They even supply new pipe clamps for the smaller diameter. They seem to seal fairly well once you get them tightened - really tight, but I'll keep an eye on it as I ride more. If leaking becomes a problem, I'll seal the joint with high-temp RTV.
They look really nice (I got the stainless steel/aluminum). Because of the oval shape, I have to be a little more careful with the swingarm stand, as the bottom of the cans are slightly lower than the stock cans were. The cans don't toe-in like the stock units. Fit was good enough to get the bolt holes to align (but just barely on the right side). The left pipe could've benefited with additional inlet pipe length, as there's a slight gap between the end of the slip-on's pipe and the OD flange at the downpipe. Quality seemed better than average - almost as good as the OEM's but not quite.
Sound is actually kinda quiet for an aftermarket model. They definitely thump instead of "puff" like the stockers, but depending on where you're standing in relation to the bike, sound level is very acceptable. They're great street cans. Yoshi claims the RS-3 Zyclones put out 90dB; so if you're looking to ride at Leguna, these will work fine.
The idle speed went up about 50 rpm after installing the Yoshi's. I hear afterburing when I cut the throttle sharply - esp. during the 1-2 shift under heavy accel. I dont' know if this is the PAIR system, which may have been muffled by the stock cans, or if it's an excessively lean mixture. Prolly mainly the PAIR and a little bit of the leanness that's always been there. I haven't noticed any surging or hesitation, and power is still there when I need it. Can't tell if I have an increase in power (I can't identify 5% gains in HP through my butt - need a dyno), but at least it didn't go down. I was going to shim the needles and adjust the air screws, but I don't think I will based on what I've experienced so far. Air/fuel mixture seems to be ok with stock carb settings. -definitely don't need a jet kit. I think the next major restriction is in the airbox. Until I make a change in that area, I'm leaving the jets as is.
Overall, I'm very pleased.
btw, if you're in the Ft. Wayne, IN. area and need to visit a Honda/Yamaha dealer, House of Honda/Yamaha is a great place. It's not the biggest shop in town, but it's family-owned, and the guys there are good folk.
--2000 VTR1000F Super Hawk