Forged piston are good first step in ensuring the life of your motor when increasing boost. Cast pistons without a doubt fall short of the task when introduced to these high pressure levels over extended periods of time.  Knowing this fact, Toda has released a forged piston kit for the Evolution X’s 4B11 motor. The kit comes in two variations, one for a compression ratio of 9.1:1 and the other for 9.2:1.

[source: toda]