Hey Sapper, sounds like a cool project, I have a new DOMA pipe for a 03 KX125, 200.00 if you want it. Williams Motowex also makes cone pipes, I talked to Jesse the owner about building a stock bore cylinder for my 04 cr125 2mm stroker crank,2mm overbore engine. I didn,t ask for the overbore, cr,s exhaust port bridge is fragile when overborred, it doesn,t sound like a 125 at all anymore, very impressive pulling power though. A overborre piston is 30.00 more also, have to drill 3 lube holes in piston, that,s a pain. I bent and pounded a 03 KX 125 BUDD HGS pipe onto my 04 cr125, I got the info that KX pipes worked on CR,s, that,s why I have the KX pipes. I only take 34 hours off a week, so I don,t have much time to be on the site. 10-4