The studs on the engine are about 7mm and the holes in the flange need to be 1/2" for it to fit without cutting off the ends of the flange.
You can call me crazy but I was the first one to buy the RCH exhaust here. It was made for the Honda CRF150F and CRF230F. I took notes from the guys that were buying the stainless steel full exhaust and it led me to ebay to find something that was cheaper and cut weight. It does require mods to make it fit.
What makes this website great is people post what they have done and give other people ideas.
