Originally Posted by Howard Cho

The FX 12 T03 and T03M are the same, both are 3ports modified with EFRA legal spec.
The FX 12 T03T is the 3ports modified with IFMAR legal spec (tear drop on the crank)
The FX 12 T03S is the 3ports stock, which comes in hardcoated crank but none modified sleeve/piston

You should notice a big difference only at big/high traction track. For a small track the T03S is more than enough.

Hope it helps!