i have the powercore 4 and i like it. most people on here will tell you to get an HMF or WB, but i like the FMF pipes. as for mid-top end power, im not sure. if there is a dyno around your area, see if they can put it up there for ya and test both pipes. you should probably only need 2-3 runs for each pipe to get some good results. just one question: why mid-top end power? are you racing or what? if you are just riding trails, i would think you would want low end to mid range the most. anyway, good luck, i think they are both good since they are FMF, but thats just my opinion.