I got a 5s hyperion in my muggy with MMM and 1520. No probs with the run time, but it seems a bit slow...I'm runnin a 13t pinion and 46t spur, and I want to do standing backflips..possible with a 1520?

I'm assuming you're using a center diff... it looks to be a little under geared... the 1520 produces a lot of torque, so it will handle a lot more load...
can you give us some more info on the setup? weight, wheel/tyre combo and diff ratio... I think you can try 16t to 18t pinions... use the
Vehicle Speed Calculator and see what kind of speeds you'll be getting.

Alien

ok
stock everything except front and rear diffs are the nitride ones, got a inovative chassis. all stock otherwise...
the motor was pretty hot after running it geared the way it is...will undergearing cause heat issues like overgearing would? I'll use the calculator and see what that says.

High motor temps would be under gearing (did you record the temps), high esc temps would be over gearing and some sort binding or strain through the drive train...
lets see all the numbers when you're done with calculator...

Alien

i was running 13/46 on my truck... It was just the right speed on 6s with my heavy elephant. So 5s would be quite slow. Definitely gear it up considering your truggy isnt that heavy either.

OK I'll try to gear up to a 16t and see what happens thanks Angry Alien and Jahay.