I decided to try the XZT+2000 tune in my new XZT+... I'm thinking the low speed trailer towing will want the agressive bottom end tune. What a PITA. Neither of my XP computers had the .net 3.5 network needed. The Quadzilla instructions are confusing, though all there. It took a nervous hour with both my desktop open to the instructions and (on the second try) the programing done on my laptop. I suppose one could print out the instructions... but you really need them. I think (hope) I got it done. Hopefully additional tuning wil not be so difficult.Russ