SlidinRX7

I just did a search on it, but came up with a lot of posts asking about the characteristics of it and blah blah blah. I know the bolt is a 19mm, but my question is how am I supposed to take it off, with an impact gun? Another question is, what size belts will I need now that I am going to be running the underdrive pulley? I still have the airpump.