Bought a 07 head from derek and he did a mx/dune port job on it. I put it on my 40hp quad (with a cam mod, JE piston, yoshi pipe and FCI intake) and i was beating up on 50hp quads with ease. There is no doubt in my mind that it is becasue of the porting job he did. Derek is fast and reasonably cheap. I will definately do buisness with him again in the future. Keep up the great work Derek