-9 to +9, he sounds like he is only a beginner. If you gets nervous and slams the throttle down then he will get a bad boom strike.

Pitch

A begginers setup should be +2 to +10 with +6 in the middle. +6 should get you a good hovering headspeed. Put about 30% expo in and set the rates to 6 degrees cyclic.

Engine

You should ask poeple online what settings they are running on their YS 61 with your muffler. Get their settings and and set it a few clicks richer. Later on you can set it to an optimal setting, but you want to make sure you don't run lean. If you hear a grinding sound like you have a problem with your main gear while hovering, then the engine is lean. Remember that.

gyro

If you don't have a gyro then get the 401. In a beginners state you can leave the gain at 100%, if the tail shakes lower your headspeed. I notice that a 401 with 100% gain can't take more than 1600 headspeed, but that depends on other stuff too. You just need to set the direction and plug it into the right channels. Rudder and gear if you have a 6 channel. Rudder and aux2 if you have a 8 or more channel.