So installed pro comps 1.5 inch lift springs to fix the sagging in the rear. So now the front sits a little low. So what is the best way to fix this?

 

Little bit of a T-Bar crank, or BJ Spacers if you're feeling saucy

 

Not sure what other's opinions are, but I'd give the rear springs a couple weeks to a month to settle a tad (really won't be that much) before you do anything to the front. That said:

Easiest/cheapest is to crank the T-bars a bit, or you could get some ball joint spacers, and back off the T-bars to the desired height (and some say get an increased wheel travel...I'm not 100% sure about this)

I've even read some recommendations about having the bj spacers machined down to 1" (down from 1.5").

there's lots of opinions for and against the bj spacers, so read up and at least make an informed decision.

either way when your front's done, go get an alignment.

 

I would take the new spirngs out wheeling, really flex em and breax em in.. see where you sit and either slighty adjust the tbars or BJ spacers, like SacRunner said.