If you can play the amp loud enough to get close to the distortion you want, you may just need a boost pedal to push it over the top. I don't like having a lot of pedals to mess with, but I've found the Bad Monkey to be a good, versatile option. The distortion can be dialed down, leaving a faily clean boost to allow the amp to sing for you. And there's lots of grind available when you want it.

A wah pedal is basically an adjustable tone control. A good thing to have, but it won't make any distortion for you.