I machined my intake, the carb. side, then blended the other sides to match. For anyone familiar with machining, I ended up with approx. a 64 finish, maybe a little rougher. I can run my finger nail in the intake and feel the walls (my nail bounces against the walls). I haven't been able to ride it yet, but I did reinstall it and start it up. So far, it responds well with no flat spots or hesitation. The real test will come later.

 

yes bigshow a friend of mine ported his DS intake smooth, jetted accordingly, then roughed it up and got much more gain. smooth is bad, but what level of rough is best I do not know. of course, polished exhaust is good because it can help inhibit carbon buildup, but you need the atomization that a rough intake provides.

mine has a spiral made from putting a slot in a bolt shank, and slipping strips of 50 grit emery cloth in the slot, then mounting the shank in the die grinder and working it in and out of the manifold. is this better than leaving it even rougher from the cutter bit itself, or should it be a little smoother - say 80 grit? This I do not know, but what I do know is that the way it is yielded me enough extra power that it was easily noticable riding without any dyno proof.
i think i will try it .ill let u know how it turns out.

 

oops....lol...looks like i messed that quote up....lol