RPM Manufacturing is not affiliated with Rick Peterson in any way. Two different companies. Your 540 kit from RPM Manufacturing will rip. Some people have stated that they do not like the 540 kit from seat of the pants riding or racing. I currently run an 88mm bore (523cc) KX500 which flies, and I have also run a 90.5mm bore (553cc) with a CR500 piston, and it was just as fast, but had more low end. As far as RPM Manufacturing goes, your dealing with people that have been building championship race motors before some of us were even born.