I scored a Pocket Metal Muff from Craigslist for next to nothing & I am surprised at how good it sounds on bass.
Used it at a gig the other night & it really cuts thru .... I use a dry blend of course (Schism) so most dirt pedals will technically work but they def don't all sound the same.
It can sound more overdrive'sh than I expected especially for a "Metal" pedal or totally evil sounding drop tuned with the mids scooped
The Pocket Metal Muff is cheap & worth the money IMHO