The differences between the Ninja bo1a and MRT was the MRT was 'tuned' had a filled and counterweighted crank and ceramic bearings with a Magnesium head. The Bo1a I had was good but the MRT was awesome. A friend had the the MRT so I didn't have first hand experience comparing it back to back against the the Bo1a but did have a comparison running the Bo1a aganst the speed and V-Spec. What i can tell you is the throttle response and power of the MRT was much better then the Bo1a. However, the MRT was very finicky tuning. Much more so then the speed. Not including the MRT my engine choices would be #1 Speed, close #2 Boa1, farther behind #3 V-spec. I've got a couple of axe Cobra X1's this year so when I start runing them in a month or so i can add it to the comparison. I'd also like to get my hands on an OS Ninja engine.

From pictures on a european website it apears the crank on the GRP tuned .21 has a filled crank but is not counterweighted. The engine may still be balanced by having a lightweight piston and conrod? Too bad I'd have like to compare the MRT against the speed. I still may have a chance my LHS still has a new MRT in the show case. The only thing is parts are non-existent for the MRT and if I do find them they'll cost as much as the the whole engine and the engine alone costs $600.