The opposite if compression is not a gate, it is an exciter (like a Sonic maximizer) or a boost pedal. In short something that will increases the dynamics if the thing you are outputting.

I think you are looking at a compressed overdriven sound as opposed to a distorted sound. The easiest way to get this is with an overdrive type stomp box, check out the boss US website they have a lot of info about the different types of useable distortion there.