installing new cam and heads on 5.3L

i have a stock 5.3L engine with only general bolt ons.  cold air intake, headers, gibson exhaust, and 11mm wires.  i have purchased a stock set of heads to a 5.3L and had the valves changed to 2.00 1.57 valves with comp cams beehive valve springs and titanium retainers.  i want to put a bigger cam in the engine but im not sure what size to use so i dont mess with the computer.  i want to put the truck down to about the 13 second quarter mile with an all motor truck.  can anyone help me?  

You need to go ahead and plan on getting a tune put on the computer for your cam change. Any cam mild enough to not be "noticed" by the computer isn't gonna provide a sizeable enough performance benefit for the work involved in changing the cam.

Here's what I'd suggest you do:

1. Take the set of stock 5.3L heads you've got and have them fully ported, three-angle valve job, the whole nine yards.

2. Contact Comp Cams or Crane, tell them the mods you've done to your heads and have them help you select a cam that will work best for your setup, and give you the performance you're looking for.

3. Nix the beehive springs for a set of Comp's LS dual springs. The dual spring has better performance than the beehive

4. Order a set of heavywall, one-piece pushrods. These are a must with an LS cam upgrade.

5. Get a set of Crane's LS roller rockers. They fit inside the stock valvecovers with no modifications, and are some of the best performing LS rockers on the market. Don't let anyone talk you into shaft mount rockers, you don't need them. Using these rockers will also let you better adjust the valvetrain for maximum performance. (The stock LS rockers use a net/lash system that doesn't provide for any valvetrain adjustment)

6. Find a good local shop that can tune the computer on your truck after the cam install, or contact one of the tuning companies (like SLP, SCT, etc.) and see about purchasing a handheld tuner that you can use on the truck.

7. If you haven't already, look into getting a posi unit installed int he rear on your truck. This will help make sure you get all the pwoer you can to the wheels, and help eliminate some of the wheel hop problems that trucks typically have.

8. Invest in a good aftermarket timing chaing for your 5.3L that'll take the hard driving the truck will see at the track.

I used to work for Crane, we once took a 4.8L engine in a truck and had it make a little over 280 HP AT the rear wheels with just valvetrain mods (no head work), which means the motor at the flywheel was probably putting out between 330 and 350 HP.  

I agree with 55Guy that should produce some decent HP I have an 04 with a 5.3 and bolt on's and a programmer. I programmed my ride on stage 3 of 5 settings and managed to reach 123MPH at just over a 1/4 mile. My cold air system is a bit larger than most since I use a Mac Pro system instead of a K&N or Airraid. I also run a 3" exhaust with an Imco racing muffler which is supposed to produce 20% more flow than Flowmaster. The combination works for me and my truck has posi with detroit lockers and will flat light em up!. I don't run it quite as hard now because with 106,000 miles on it and parts being as expensive as they are for these new trucks! well you know. Good luck with your project!