On an LSJ, a 3.0 is good for 15psi... and the 2.8 is good for 17.5psi. And I thought that all Ecotec Crank Pulleys were the same. Iono... just what I thought.
In all reality... its all about restriction. Free Flowing exhausts and ported heads will lower the amount of boost that you are pushing.
MAybe thats it but im only running 2.25 throughout the whole exhaust besides a 3 inch inlet muffler but I have a LSJ manifold that I ported out as well and its catless.