Can anyone suggest how I could give my guitar a nice thick, growly tone? I play a standard 4-string Fender Jazz Bass (Mexican-made, so the tone's not all that great in the first place), and I play through an 80 watt Peavey Basic 112. I also detune a lot, sometimes down two whole steps. It would also be nice to get a convincing slap sound out of it. Are there any amp or guitar settings I should know about? Or maybe there is an effect pedal, such as an overdrive pedal, possibly, that could help me achieve this sound?