i am not a tamiya fan, but i have a friend who has a tt-01.
-Get ball bearings, they will really make a difference.
-oil filled shocks are a major improvement over the stock friction "shocks".
-get a decent ESC. the one included is OK with the can motor and 27 turn motors, but will probably smoke with a modified motor.
- and most importantly : Have fun!!!
Cheers!