I've recently bought a 09 wr450r off my boss brand new only has 200k on it so it has barely been driven not even beat in yet. I had plans on getting an fmf powercore4 for it because my friend has a 09 klx450 with stock exaust and his motor overheats quite frequently. I'm afraid my bike will do the same which is why I want to put a new exaust on it.. Is this a good idea? also when I put the powercore4 on would it be mandatory to rejet my carb as well? Any bit of help with this topic will be greatly appreciated. Tell me any opinion u have.. Thanks.