I would not recommend either!It's ordered 5star tuner with sct handheld. I have a 2013 fx4. Question, is it bad to launch in 4x4? Is it bad to launch with electric rear locker engaged?
Heck, anything can be used at least once ....You can use it on pavement. You aren't going to mess anything up unless you get wheel hop or axle wrap. In which case you would break a LSD too. Either get traction bars or use some common sense and if something goes wrong, take your foot off the gas!
Normally with a locker it wouldn't hurt anything to race with (as long as it's made to handle the power you're laying down), but with ours disengaging at 25 it creates a scary situation if you get wheel spin off the line.From what I've read, the instant traction on dry pavement while using either of those is a horrible idea.