high compression piston...??

[4yama2rider6]

i am in the process of buying an 01 400 ex...id like to pipe it jet it and throw a high comp. piston in it i read on here you shouldnt go over 11.1 with a stock rod and to keep it running on pump gas...what is the stock comp. ratio for a 400ex and will i notice big gains just from the piston or not.....and what is the difference between a trx 400 and a sporttrax 400 which is better...and how can you tell them apart..thanks!

[400exrules]

i too want to put a high compression piston in my 400ex, but stay at the stock bore. you can run up to a 11:1 on pump gas(93), but anything over that will need race gas. I would go with a 10.8:1, like im going to do, just to be safe.
i belive the stock compression ratio is 9:1, correct me if im wrong tho. And the only difference between the trx 400, and all previous years, is the trx has reverse, changed gearing, and 450r style plastics....it is also heavier.

If you do get the high comp piston, you should get a cam too, im getting a cam soon....and the piston later.