I am looking to buy a 2005 or new YZ125. What are the best mods to look for on a used bike. I saw a one with a big bore kit 144 do these run good? reliable? Do they mod the carb to compensate? What pipes are good on these and where do they increase the power? What gear ratio are you guys running for MX? Who does a good port job on these? How big improvement? Big bore or port job?