Thanks for the replies guys,
I had some flights yeasterday with the 12 tooth, and dropped my headspeeds 100rpm to 2000,2100,2200 with the castle spitting out the warning @ 2200 but performs ok.
There did not appear to be any apparent difference in flight time, or temp but havent checked the logs and it was a hot day 37 degC.
I will definately pick up a 13 tooth pinion, however it flys smooth @ 2100rpm and i might get to like it.
I will also look at changing the bullet connectors but its a complete PITA and annoying!!