Jeff,
I agree with Oldrodie, you will need some degree of back pressure to maintaine low end torque.
That be said while at the NH rally this week end we had eight bikes dyno'ed and a couple of them had straight through TORS and the result of the dyno's showed no loss of torque on the low end.
RobBA05 will be posting all the dyno charts with each bikes setup and you can check yours against theirs.
