I was talking to a friend who has a Thrush glass pack on his TJ and he said I wont get any more power if I go with a Flowmaster and also the glass pack is cheaper. Is this true? If I go with the glass pack, will I see the same or near the same results as if I went with a 2.5" Flowmaster 40 series? I really like the way his sounds with his glass pack, but I will sacrafice the sound and money if I can get more power with a Flowmaster. Thanks a lot.