could someone tell me what tire compounds at maximus 13.5?

Lots of different tires can work. My personal preference.....

BSR
RR - Dbl. Pink
LR - Pink
RF - Dbl. Prpl.
LF - Pink

I use two sets during the race day. When I finish a run I clean the set that is on the car with motor spray and then put the other set on for the next run. Repeat the following run.

If you run whites and greys you can eliminate the cleaning and set rotating.

With exotics I've had some luck running......
BSR
RR - White
LR - Pearl
RF - Grey/Silver 70/30
LF - White

For me the pinks and purples have been faster and they wear a bit better. others have found whites and greys to be faster.

why do you use two sets?

It gives them some time to dry out in between runs, so they stay more consistent and get less gummy.