Currently, I have Hooker LT headers and o/r x-pipe hooked up to my stock catback exhaust. Although the headers and x-pipe did increase the sound, I would still like a little more thunder from my exhaust but not too much. For catback exhausts, I've narrowed it down to Magnaflow ($345), Steeda ($539), and Bassani ($650). Since I have a convertible, I am concerned about the infamous drone of aftermarket exhausts. Any suggestions? Also, is a 5-7 rwhp gain reasonable?