No more than any other tunes, customs might be worse in the long run. But I think these ZF6s are about bullet proof. Funny because they're rated for 520lb/ft torque input and yet come on a truck that's 40-50 over that stock.
Will say that I still recommend a SCT with pre-loaded tunes...Still got 4 canned tunes with some user adjustable options (EGR on/off, Turbo brake, tire revs) and on top of that can get custom should you ever start to want to try custom. Only bad part is how long it takes to change tunes and that you can only switch vehicles 5 times before spending more money to unlock it.
Last edited by jerg_064; 06-03-2012 at 08:06 PM.