What is the fastest inline reg I can get?

Lets say I wanted somthing that can keep up with an xvalve.. 20 bps...

I know your most of your opinions will be you dont need inline reg on xvalve I agree but I have many other guns including cockers and sheridans.

I am going to buy a very good inline reg soon. I want to know what the best fastest reg is..

I would prefer it to be a flat black low prileish. Like a palmers stabilizer..

Thank you