I don't have a TCU tune or I'd speak up about it. But, what your asking the stock programming already does. I enter corners, or a set of corners at 5500 or more all the time and the car holds the gear. In S mode it won't shift until redline stock so I think your good to go. What I'd like is to be able to upshift before redline in certain situations even though I'm in manual or S mode and not yet at redline. After I iron out a few more pressing problems I'll be digging deeper into the TCU tunes myself.

Les