The gnarlies are great pipes IMO, They Increase bottom and mid power with AT LEAST stock like top end (I think maybe a little more on top, but I have other mods). I wouldn't worry about reed spacers, I would just upgrade the air filter setup, If you havent already, and run the gnarlies. I have the gnarlies, K&N, 3 degree advance key, 145psi head, TDR reeds, and I went up one tooth on the countershaft sprocket, Runs Fantastic. My .02