the first set of longtubes i had were the pacesetters, i believe i gained 14rwhp and 15 ft lbs. of torque to the rear, they were the ceramic coated and if your going to spend the money, i would go stainless, kooks, qtp's. There will be a noise difference depending on the cat-back you have, i had a GGMG chambered cat-back and i liked it, loud and throaty, but everyone is different, heres a vid link of an ss with bolt-ons, to give you an idea of sound.
http://www.streetfire.net/video/camerows6bikes-more_54761.htm