I installed a Yoshi RS_3 on my 2002 wr426 two days ago. I checked my plug a few days before I installed the pipe, and it was a bit on the black side(leading me to believe that it was a tad bit rich). It had always started on the second or third kick. It has aprox 60 miles on it total( I bought it new as a non-current model about three weeks ago). After the new pipe was installed, it started on the first kick every single time. I called one of my more knowledgeable friends over to look at it, and he took it for a brief ride and said it seemed dead on to him. He said that it had no lag when rolling onto the throttle and no popping on deceleration. The header pipe had never really glowed before the installation of the Yoshi; however, it glows on the first three or four inches of the pipe now when it is idling. I know that the best way to tell is the 'ol check the spark plug method; however, I don't have a legal place to test ride it before my next bike trip this coming week. I am very un-knowledgeable about carb jetting. If there is a good chance that it is too lean, I will take it to the dealership and have them check it out. I would rather save some cake and do it on my own, but I don't want to frig up the engine either. What thoughts do you have on this. Thanks in Advance for your time!