I was at least .5 to 1.3 a lap quicker last year with the 19T pinion over the M03. In A1 and A2 I lapped up to 4th position with the M04. Corner speed the 03 dosen't stand a chance they do turn-in harder but mod to end the 04 will walk on the 03. The key is the front tires most set the car up with the SG radial. With B's the car is a whole different animal.
For break-in water dip is the only way to go leave about 2-3mm in the center and it is just right anymore and the motor will start dragging by the end of the mains. Can the Buchi Old Johnsons are the only way for open club racing the new Johnsons have big torque but not alot of rpm a good one runs in the 12K range. For Nats a little tip for those participating. It is tempting to run the old worn-in motors that have the big HP and big RPM but you WON'T be racing this motor. Get yourself a brand new johnson and break it in at the track or home and spend this week with it and maximise the speed it gives. Last year the gearbox rumors flew when I stayed the same speed as I had been doing all week in practice and most of the others lost .2-.7 a lap. Guess what I had been practicing all week with new motors we were going to race on Sat and Sun. Save the good voltage for when nobody is looking.

Sorry it's so long