Nice update! That's what I have in mind if I keep the Attak next year. It just needs more surface to float the rear on top of the POW. I've done 3 Hartman kits on Vipers. The thing that I question from Tom's kit is that the tail extensions seem to be too long for what you are trying to accomplish. I have in the past shortened the tunnel extensions to better fit the extra track length. Did you try fitting the 144" under the exsisting tunnel, seems as though it may, fit but be very close to not. In my calculations a couple of inches longer is all that should be neccessary. Great job! Let us know how it does in the POW. What profile track did you use? Also did you add the No Slip (internal/external) drive sprockets?