Ive done the WEXCR and KCCR a few years ago and been to several GNCC events but didn't compete , my buddies did and still do. Never ran a 350 in one but can get yu ready to go. First and foremost make sure your quad has new bearings/bushings, No leaks. Basically you want your quad in tip top shape maintenance wise. When it comes to buying parts, 6 ply tires and belly and rear skids are a must have, Tether switch also. You want to be comfortable as can be, Most events last an hour and a half to 2 hours depending which series. I cant stress this enough, Seat time is your best advantage, The more you feel comfortable and know your ride the better off you will be. Reliability, I would rather have a stock motor quad than any built. Most Pro XC1 and XC2 guys are running stock motors with full exhausts, air intake setups, Carb and CDI upgrades. However I know of several that do run modified motors but everyone has their own preference. Most of all HAVE FUN, BE SAFE. One last tip it does not matter how fast your quad is, without a good suspension setup your only hurting yourself, Ive witnessed little raptor 250's and Apex/DRR smoke 450/660/700's in the woods just because they have a top notch suspension setup.