What are the tophats exactly ? And what is the advantage of them ?

 

tophats are required for install your koni and gc together, they are what holds the suspension setup together. You will be reusing your stock tophats when you install your koni and gc combo. By the way thats a good set up.

 

Are the aftermarket top hats any better ?

 

^only if yours are shot. other than that, it should be fine.