2004 GM V8 5.3 Z71
installed Gibson headers, flomaster catback, k&n intake. Truck ran hesitant and shitted up the dual pipes with soot.

I got a Predator and been messing around with that. Timing +2% and -2%
fuel. It's running a little better, but i want some advise before going any further.

 

where did you get the predator? if you got it from running with the devil then i think johan will give you a free retune on it and can do via email. that would be your best bet. unless you are getting ready to step up to a custom tune. the soot os aleays going to be there.