stock pipes on all yamahas suck...that's why they're so restricted from the factory..

the best stock pipes made, are by Honda..

 

I could go with that. Thats probably why the 400ex gains so little with an aftermarket exhaust.

 

its been prooven that honda doesnt restrict thier motors as much as other manufacturers do with exhaust. honda usually chokes them with small carbs, jets,thick filters,etc.............

 

ding ding ding! we have a winner..lol

ive heard that the 2004 400ex has a larger carb than the other years...I have never gotten any real proof though. And as for 2005, Honda STILL hasn't released any information on the 400ex....Hopefully they're spending some time in R&D, hoping to catch up to the z400. That'd be nice...