I just bought the slp "loudmouth" for my 2003 gt (stock) and i wanna get the slp o\r x-pipe. 1- how much more hp will that whole system give out and 2- i knno every year im gonna have to put my cats bakc on bc of inspection how long does it take to do that and is it easy or hard im sorry if this sounds noob but im 16 and jsut got my mustang and i bought it to mod