i just used the 400rwhp highboost and 360rwhp highboost tunes from duramax tuners tune library. when i drive around the brake service light comes on with those tunes and the brake pedal feel is really really bad. i put the 40hp tune with turbo brake on and it goes away and stock setting it goes away too? any help would be nice?

Give Nick a call. He will beable to help you.

I had the same prob...Go in the tune And set the revs per kilometer to 405.

in the speedometer callibration??