Both are way too large for stock stall. Notice how they also say they are made for the L99 engine in the camaro, not exactly ideal for a heavy *** truck.

This is also where you gotta remember that you have VVT. So you can either keep VVT or delete VVT.

Stick to something like I already said, 212/218 or close to that.

 

do i want high lift or low lift

 

or what do u suggest

 

Low lift is just fine on a 5.3.

 

i know i need diffent push rods but can i use stock valve springs

 

No, needs stronger ones.

 

would i be sacrificing power if i stayed with stock headers and y pipe with cats

 

Yes. Headers move the power band up in the rpm range.

You can do a PAC-1218 spring and reuse your stock retainers/seats/locks.

If you do a double spring, you have to change it all out. Just means more money.

 

what woud be the best choice
usining stock exhaust manifold and have the cats removed and just replace the muffler
replace with long tubs and off road y pipe with a new muffler'

i just want to keep it quet ish with the new cam so would the cast manifolds keep the nosie down or woud they cut the flow and sacrifce alot of power