Umm... 'fraid I don't really know what you mean by "buffet/shark", but everything vibrates a whole lot... hope that kind of helps.
As for installation of the pipe/jet, I didn't do it. That $150 included 45 mins labor.
That reminds me of another thing, though. I think that the vibration caused a screw to vibrate loose, causing a fuel leak. The screw in question is one (I think) that holds the carb on the intake. It was just a matter of tightening the screw, but it's in an inconvenient spot on the underside of the motor, so I had to make sure that the fuel was turned off to keep from getting gas in my hair. It's also one of those things that you have to keep from overtightening, or else you ruin the carb.
Besides that, I've seen postings all over the place about vibration problems, discomfort, things vibrating off, etc., so make sure you're willing to deal with that. I still like it, though.