I just got a 2007 Grizzly 450. Im disappointed in the top end performance. this thing is slow! How can I get some more top end?

 

Your best bet would be to sell it and buy a bigger displacement quad. If you are already dissappointed with the performace of the machine it will only go downhill from there. However some temporary fixes could be a slip on pipe, bigger tires will allow more topend speed as well. Aftermarket air filter might help a bit too.

 

Bigger, Bigger and then, Bigger. It's doubtful that you will ever be satisfied with the 450 if you are wanting fast. It wasn't made for speed. I have an 08 that my gf rides and it is perfect for her, but I couldn't stand it for myself.