k i was wonering if any one has used some glass packs on there mustang and if so how good do they work... i dont really want to spend to much money on a exhaust system at this point in the game and was wondering if glass packs would be a good cheap choice... but my concern is that the glass packs will rob me of horsepower.... my engine is going to be about 500 horse when its done and i dont want to take that away from it threw a my exhaust....