I have a LQ4 in a 01 2500 with a ported and bump mod throttle body, Pacesetters, e-fans, Airaid tube w/ K&N drop in, Wait4Me tune, and 3" true duals (not mandrel) through an x-pipe but with factory cats. At what point should I consider fuel upgrades? What kind of HP at the flywheel am I around?

 

with a stock cam Id say your fine with stock injectors...depending on the cam that you swap in, it would be wise at that point to upgrade your injectors

 

Your fine with what you have, no need to change.. Your prob around 330 or so crank hp.. You will be close when you slap a cam in,or a blower or nitrous, get a retune, untill then your good as you really don't have a huge amount of mods..