My brother got a 06 450 R around Christmas time and we noticed that something was different with the throttle, the responce was delayed. We thought that it could just need time to be broken in. Last week he brought it to the shop and they said that a Jet kit will solve it. My question is should the throttle be like it was or should it be more peppy? Also should he install the jet kit?

 

Throttle should be way more peppy. Should want to lift up the front end when you romp on it. It does sound like a jetting problem. They're cheap so I would get one and install it.