That is a high voltage for the TPS. If I'm not mistaken the higher the voltage the more advanced the ignition timing is at all throttle positions.
The regular/premium key settings switch between two different timing curves. I bet you'd see the deto sensor go off less often on the regular setting as the sled is currently set up. The regular setting pulls a couple degrees out of the advance, while the premium setting is a little hotter curve.
To check ignition timing you'll need a timing light. I've read you need some special two stroke compatible light but have no issue using my regular strobe timing light. I use my truck battery as the voltage source, clip the magnetic clip over a plug wire on the sled, point the strobe at the opening atop the ignition housing, and with sled running (TPS unplugged and motor warm) squeeze the timing light trigger then rev motor to 3300RPM and see what number is illuminated. Stock spec is ~29* BTDC, SledGuy says advance it 4* for that 910cc, so you want ~33* BTDC (seems like lots of advance!). The adjustment requires pulling the flywheel, loosening three allen bolts that hold the stator in place, then turn the stator clockwise to retard timing or counterclockwise to advance timing.
I'm not sure about the compatibility of those two TPS's. It shouldn't go to open though, so I think you are correct in replacing it. But of course swapping to check could save you some $.
