I don't think the Metal Zone is what you're looking for... that's a distortion in it's own right. It won't work well with amp distortion (well, I do it, but that's 'cause I think it sounds cool, it's not a very "nice" distortion).

I've read a lot about the Fulltone FatBoost. Here's the manufacturer's link: Click here

But I've also read some reviews that say that there are other, better products. I have yet to try the FatBoost or other similar products, so I can't say for sure. However, the FatBoost does sound like what you're looking for.

I've used an EQ pedal before as a boost, also my compressor can do some interesting things and help me cut through the mix, too.

What other effects are in your chain?