If you really like your 400EX (its motor anyway) I wouldn't put on a turbo. It's like running with NOS on quads,its not going to last long,but for as long as it does,your going to be in for a helluva ride.

 

http://www.paatving.com/Articles/tur...turbo400ex.asp

 

Thrust: Nitrous not NOS. NOS makes nitrous systems. Everyone must understand this. Secondly a turbo does run on lower compressions then an NA motor. I bet these turbo kits are pretty reliable. Nothing compared to the reliability of a stock or NA moded motor but for the increase in power it is probably better then boring to a 465, stroking, and running alky. the reliability factors are probably very close.

 

Well i have still been thinkin about it and if it is like our trucks then the turbo will never hurt the quad as long as you keep your eye on the pyrometer to make sure it dont get in the red.