Apart From Tyre Change: Nothing.

The TT-01R is indeed the Race Spec TT-01 with Ballbearings, Alloy Prop shaft and Oil Filled Shocks Standard..
There is Nothing You need to Change at all..

On a Stock TT-01, the only Changes you need to make it Drift is an Alloy propshaft and Wheel Bearing kit..
People have had a "Bouncing Issue" with a Stock TT-01, this isnt caused by the Shocks this is caused by the Stock 27T silvercan not producing Enough High RPM to keep the Polypipe Tyres rotating Quick enough.
Oil Shocks are not essential,they are a good upgrade but not essential..

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