ok so here is the deal i have a 2008 specail edition yfz 450 and just bought a yoshimura trc competition series slip on pipe. I will be runnin the stock air filter with lid on. I was just wondering if anyone else has done the same thing for their yfz and where they started with jetting. I have jetted a few bikes before so im jsut looking for a starting place. i have heard around 158 main jet is the thing. let me know if you have any advice or have done a similar thing....oh and i live in iowa so theres the elevation, no mountains or anything, THANKS