1999 to 2003 vs 2004 and up 400EX
 

i read somewhere that the 1999 to 2003 400EX's dont have as much power as the 2004 and up models, i was wondering if anyone can confirm if this is true or not?

i dont know about that, but according to the specs the 04 and up have a 38mm carb, the 99-03 have a 35.5mm

that could be what the power difference is from, thanks!