can 2006 trx90 plastics fit on a 2005 trx90?
and is there anything i can do to a stock trx90 to make it faster?

 

Idont know about the plastics ,but they problay will unless there was a frame redesighn,go to a honda shop and observe the frame on the new model and see if it matches yours ...as far as going faster with out mods good luck ,youll have to buy somthing..unless its like the 70 and u juist need to need to remove the screw preventing full throttle ...it's located in the housing that the throtle comes from on the handel bars ..on the trx70

 

sure, there both the same