MY 03 SWB HO 6SPEED 3500 GOT 18. 9MPG THE FIRST TANK. IT HAS A 3. 73 REAR END AND HAD 50 PSI IN ALL TIRES. ALITTLE MORE AIR PSI WOULD HELP SOME. QUITE AS A MOUSE BUT QUICK AS A CAT. BUY ONE,THE SAVINGS ON GREASE SHOULD OFFSET THE COST OF THE TRUCK,IT ONLY HAS 2 GREASE FITTINGS. WILL STRAIGHT EXHAUST AND K&N HELP THIS TRUCK?FYI;WINDOW STICKER$38675 PAID $35050