Kyosho & Losi big bores are 12mm ID too ... not sure on the dingo but thought they were slightly under 12mm ID.
IMHO the main reason people have prefered the small bores to big in this country is that our tracks are NOTHING like the ones in the USA / Japan so there is plenty of work to be done with pistons to get the correct "feel" on UK tracks.
I, along with a few others, have done A LOT of work with the Kyosho big bores and now find them quicker than the small bores ... interestingly we all arrived at the same piston combination independantly ... and it has far more than 2 holes
