Nitro TC3 in my opinion is only good for parking lot bashing not competitive club racing. No one has won a major 1/10 scale onroad race with one in years.
I put a .18, .21 and a .28 in mine and went outlaw with it.
And BBB was the one who said he was thinking about putting a .18tz in it I just shared my experience when I dropped a .18tz in my Nitro TC3. BBB, Bertransv87 is right a .18tz would make you illegal for roar sanction races if your goal is to run in roar events I figured you were talking about parking lot bashing. Sorry if I mislead you.