The GMC Owners Group

Airflow equals performance. It sounds like you are off to a good start with the Flowmaster cat back system and you might already have a performance air filtration system on it like a K&N but if you don't i suggest getting one. If it is a 4x4 truck that actually leaves the pavement consider just replacing the filter element with the high Performance one but if this is a strictly street vehicle the cold air induction kits do provide about 5% performance gains over the filter replacement option. Once you have done all you can do for the air flow it will be time to look at the ignition system. Be sure to use high performance spark plugs like the E3 plugs that are suppose to add another 5% performance to the motor. I use them and love them and recommend that anyone reading this try them. The use of synthetic fluids also increases fuel mileage and does free up some friction from the rotating assemblies. You can look into under driving your accessories with pulley swaps but these tend to be expensive. There is always the option for turbo charging, super charging and nitrous if you budget permits but. There are many many more ways to squeeze power from a motor also like dropping the temperature of your thermostat from the factory 195 degree unit to a 160-180 degree one. This tricks your fuel injection system into thinking the truck is cold and sends more fuel to the injectors to warm it up. The list can go on and on but i hope i have been helpful.

Sounds like you just want to drive like an ass.

Best thing to do is to Dyno tune your truck to your preference. Here is a link that should help you get what you want out of your 5.7L. I have a 96 jimmy with 4.3 and Dyno tuned it and have over 365,000 miles on it, still original engine and transmission, rear end. Last know pull on the Dyno was 220 HP at the rear wheels before I turned it to AWD and did more Dyno tuning. Here is link that should help you get what your looking for. http://www.exatorq.com/HomePage

List done on the 4.3
Removed the MAF screen
Removed the throttle blade restriction plate
Cold air intake
2.5 cat back and high flow Cat's Magnaflow's
Replaced 5.1:1 rocker ratio to 6.1:1
Transmissions mods 4L60E
Replace the Servo with Corvette servo
Replace the Boost valve with 0.490", had the 0.500" but found that to harsh of a shift.
Installed a B&M Shifplus electronic shift improver B&M part #70380 $45.00
Dyno tuned to 120 MPH was higher but brought it down, Shift 1-2 at 3,300 RPM....shift 2-3 at 4,400RPM.... shift 3-4 at 4,900 RPM at WOT.

Good luck and keep us posted.