Correct if I'm wrong but aren't Ares gearboxes proprietary in some areas?
If you run a 7.4v LiPo, 13:1 SHS gears will do just fine on standard spring but on an 11.1v LiPo you start running into problems on that ratio. If you go inside the gearbox, you'll want to check for perfect compression which you should look up guides for if you are doing all of this yourself. If you run 11.1v LiPo's consider SHS 16:1 or make the switch to 7.4v. Shimming guides, AOE correction, make sure that if you pick up an SHS motor that you match the pinion gear brand which is the gear on the top of your motor to your gearset or at least your bevel gear or your shimming will just not cut it no matter what.
A good place to start is a new High Torque motor by Lonex, SHS, ZCI, ASG etc and then a decent mosfet. Your motor is gonna get hot no matter what but if I was you, unless you are planning on doing some serious upgrading on the gearbox and willing to either get someone to do it or put in HOURS of learning and work, I would change the motor to a torquier one, do the shimming and then leave it at that. If you are comfortable with how the gun performs, take it from me, leave it alone. It's not worth it for the most part. Poor shimming can put increased stress on the motor and become very inefficient battery wise.
TL;DR (Basically..)
Get a new motor, preferably High Torque by the good brands like SHS or Lonex that are out there
Learn to shim your gearbox and make it as perfect as possible
Whilst inside the gearbox, clean EVERYTHING that is mechanical including the actual shell itself and reapply some fresh silicone lubricant
Check your compression parts and look up guides on testing compression to make sure it's nice and proppA because you might as well whilst you are in there
If the build is particularly low stress and you aren't getting over 30rps, I would say leave AOE unless it is seriously off, if you are willing to put in the time though...it will only help your piston live a lot longer