My brakes have the check valve, it seems to work, because when I pull it out after I turn the truck off you can hear it suck air. I took it out and cleaned it with carb cleaner when I changed the engine because it had grease on it. Maybe I need to get a new one.

There is a car club I'm in that is renting a track for 30 cars from 8am to 5pm so I will get tons of runs in. I think if I turn up the boost to 16psi I should get mid to low 11s. My bed cover is heavy as hell, and I have amps subs, and crap behind the seat, I think I could get down under 5000lbs. It weighs 5260 with me in it.

 

Try sy ty method it worked for me a was able to build 6psi off the line with a stock 4l80e converter

How to do a boosted launch:

* Put the transmission in (N) Neutral
* Rev the engine a couple of time while simultaneously pushing down HARD on the brakes. Revving the engine creates vacuum for the brakes.
* You should feel the Brake Pedal drop lower
* Keep the brake all the way depressed, and shift the transmission into Drive (not Overdrive).
* Start pressing on the gas pedal now to build up boost, it take a little while to get past 0-1 psi.
* When the boost is where you want it and it is time to hold on and go, release the brake and slam the gas at the same time.