Upgrade brushless motor ?

[RCHabit]

hello,
I purchased my set up from Mike,

it is

8XL

Mamba max ESC

I also run 2 7.4 8000mah lipo for 14.8V

Proline big Joe tires

I want to upgrade the motor for a little more speed, What does the RC monster have? I use the truck (e-maxx) on grass and hardpacked dirt roads.

Thanks in advance