Here is the question if I remove cat from pipe will I do damage to engine, and Harleys have this cat beacause of the epa?

 

If all your going to do is remove the cat you should be fine. Do yourself a favor and at least change out the pipes, remove the cat, change the ac and go with some type of fuel management like a PCV. Save yourself some time and contact Jamie at Fuel Moto he will do you right.