i dont have emissions were i live so do i need a tune,sims, to make the truck run better with the long tubes or if i dont do tune or sims , will my check light just be on but the truck will still run good

basically what do the rear o2's do?

 

the rear O2's monitor the Catalytic converters...that is all. You need to get a tune to take advantage of your LT's though.

 

so if i put sims on it all i would be doing is keeping the service engine light off

 

Tuning is the answer...for both

 

thanks