Dude, fuzz pedals and distortion pedals are APLENTY. I recomend going with a fuzz first for your style. Youtube some videos (Bass fuzz) to see what is out there and possibly latch on to something you like. Be willing to save and spend around a hundred for a quality pedal. Don't cheap out, you'll regret it.
I have several different fuzz and distortions. I think the MXR El Grande bass fuzz is right up your ally. For hardcore metal, it's got the balls to push heavy riffs. It also does a great job of holding the low end.
If you go with the El Grande Bass Fuzz from MXR, be prepared to have to learn it. It's a plug in and go pedal, but it's touchy. It took me about a week to dial it in where I wanted it and to learn where on the dials different things started happening.
Also, if your bass is active, that will have some effect on some pedals. If the pedal you choose just doesn't act right, it may not be the fault of your pedal. It may be your bass is pushing too hot a signal through it. So, try adjusting the knobs on your bass. Maybe try turning knobs on your amp as well to work that tone where you want it. It's a hat dance trying to dial everything in where you want it, but worth the effort.