I've got an 06 LT bone stock that I've put a good deal of time into the looks, now I want to move to performance, what's the best first mod?

 

Entertainment head unit?
wheels and tires?
lowering springs?
rear swaybar?
upgraded front brakes?

it’s really a matter of personal preference and budget.

 

Just installed headinit last week as well as new tires, lowering springs are up next, but performance is what I'm looking into now.
Such as engine, power,torque etc. Looking into the stage 1 tune from rom motorsports for 249$ but not sure if I have to have the tuner also or how I get the tune in the car.. been in contact with them but now I'm looking into intake injectors exhaust maybe headers, wa just looking for advice on what's best first

 

Don't do the "tune" till the mods you mentioned are done. Then it can be tuned to optimal efficiency.