Looking at buying an 07 GMC crew cab, short box, 6L. Not wanting to change anything looks wise, but what can I do as far as exhaust and tuners? I was thinking maybe just cut the cat and muffler, and put in a better flowing muffler and leave the cat out. Try to make it look as stock as possible. Don't want it loud either, just some better flow. As far as tuners, don't need anything extreme, just something to get me some better fuel mileage and more towing power. Any suggestions?