We did the swap yesterday, everything went fine. To test the gearing, I turned the brake disc and compared to the primary cog (=engine). I got 8 revs on engine = 7 revs on wheel but the other wheel was on the ground so it has to be divided by 2 due to the differential. 8 revs on engine = 3,5 revs on wheel = 0,4375. Theory says 38/25*17/59=0,438. Not bad at all.
We did some stationary tests with one side up. 5th gear works smoothly, brake disc spins really fast compared to 4th gear.
And finally, ultimate test on the road. It was like I expected : nicely high geared but not too much. The engine has a lot of low-end torque so it works great. We'll do the other test next week.
We also plan on mounting an intercooler (which exists stock for the engine) which increases torque from 16 to 18.6 mkg at 2100 rpm. This mod should also increase efficiency.
Pictures : old gears / new gears / before / during / after
