450es needs more power what to do?

[ranger400ex1994]

well i know this is really a ex forum but i figured i could post it here. My dad has a 2003 honda 450es and he can only get about 48mph on the top. now i know this thing is no speed racer but what could we do to it to get more power out of it. he was thinking about a pipe but he wants a really quite one. like super trapper or big gun or anything that is quite.

[F-16Guy]

HMF makes a good one. If you also go up a size or two (depending on elevation, temp, etc., ofcourse) on the main jet and get a high-flow filter, like a K&N, you should notice a good power gain. Here's a link to the pipe:
http://www.hmfengineering.com/eco.html
And a jetting guide:
http://www.hmfengineering.com/jetpg.html