There was a fella on here a few years ago that used Amazon parts to make his Tahoe faster. Look up the posts by
@badandyturbo. He's not on here anymore, sold the truck and is playing with twin turbo Fords now. I and others on this here forum have personally witnessed the performance gains, long tubes were good for about 25 rear wheel horsepower through the traps in the quarter mile. Gears would be a good mod too if you have tires that hook.
That cam is massive for a 5.3, traded all your low end torque and give some back up above 4,000+ rpms for more horsepower.
My 5.3 puts down an average of 315 rear wheel horsepower through the traps in the quarter mile. It was originally rated for 310 SAE Net horsepower at the flex plate. Its only modifications are a Magnaflow Y-Pipe and Cats and a BlackBear Performance tune.