Yeah, definitely if you want a high rate of fire set up you'll need to install gears to take the speed-stress as well as a weaker spring (usually a M100 or M110 at most). You'll also need a new hop up buckingl hard type bucking for speed soft bucking for torque.
If you don't take the proper precautions you will break motor teeth, strip gears, and/or not even fire a single shot.
A 9.6v battery is the best advice to raise your rate of fire. Also try to get a high amplitude (mAh) so you can play for longer periods of time.
And yes agreed, Justin is extremely helpful, very knowledgeable. He's not just a random sales person trying to make a buck putting useless parts in a gun or mindlessly upgrading.