Honestly, I found the stock 27t motor to be very capable. It provides ample speed for most trail, mud, snow and light crawling needs.

You can buy 35t, 45t, 50t and so on motors. higher the turn rating, the more torque. But gearing changes will effect torque and top speed. There is no perfect combo.

Some also go brushless. This gives the option of much higher speed without the loss of torque, especially if a 11.1v lipo is used.

But one aspect of full scale crawling applies well to RC....Have more axle than motor! If you go crazy with power, you will end up snapping driveline parts!

A standard 7.2v 5000mah NIMH battery is fine for crawling and trail driving. You can opt for a 7.4v (8v when fully charged) Lipo battery, which will increase power some and is also a lighter battery which can help when crawling. But you will be plenty happy with a NIMH battery to start with.

But, if money isn't an issue, then buying a Lipo battery and Lipo charger off the bat will save money in the long run. You can google search for info on lipo's and lipo chargers.