The real gains in porting have very little, if anything to do with how the surface is finished. If you just sanded the exhaust ports, without knowing where and how to radius in the bowls, you likely didn't help, or hurt anything. You need to know the correct areas to grind, and the areas NOT to grind. The best job a novice can hope for is to just blend the bowls, and gasket match the intake. Again, if you don't know how much is too much when blending the bowls into the seats(how much radius to leave in there), you can easily hurt low and mid lift flow. Just try to make a nice rounded radius leading into the seat/bottom cut and you should be ok. Just smooth and blend the short turns without removing much from them. As for the finish, I finish the intakes with 60 or 40 grit, exhausts with at least 120 or finer 240, depending on how much time I want to spend. Peel the rolls out a little to make a "flapper" to finish it out. The finish is really for the customer to ooh and ahh over when he pays good money for the work. JMHO.