I have a 2002 GMC Sierra 1500 with a 4.8L, 4L60E, 3.23 Rear Axle K&N Air Intake and a 1-2 Magna flow. Truck is starting to feel slower and I was Thanking of getting my hands dirty. I would like to have about 400HP or more but keep it a daily driver (about 60 a day 7 days a week). Any Suggestions would be appreciated