Can anyone put me in the right direction? Who sells the best stuff out there? I want exhaust, cdi, etc. Thanks.

 

It's a kids quad why in the world would you want to make it faster?

 

Some kids fit a machine and also have enough expierience riding and get bored with the speed of a stock machine.
Especially a 50/90cc 4 stroke. They are sloooow.

careyanderson: Maybe try Hetrick Racing for the parts you're looking for.
Also: Michey dunlaps "four stroke tech".