I just bought a Killer Ant with a 1X12 Killer Cab and I'm trying to decide which pedal to get to give me a little more gain and distortion. The Killer Ant has a British voicing and it starts to break up around the 6 or 7 volume setting into a classic rock tone. Nothing wrong with that for classic rock but which of these pedals below will get me close to GnR, Alice in Chains, or maybe Metallica? Again, I realize this is just a 1 Watt tube amp so it's a bit limited in some ways.

V2JH Jekyll and Hyde Overdrive and Distortion
Fulltone OCD
Ibanez TS9
Electro Harmonix Metal muff

Thanks a lot for any feedback or advice. I'm open to other suggestions other than what's listed above.
Bummer...my local Guitar Center doesn't have any of these pedals. Maybe I should just go with a Boss Metal Zone?
Get a new GC. Try SamAsh if they are by you. Also Music Go Round.
I wondered why the frisbee was getting bigger, then it hit me.
I think I might just go with the Robert Kelley modified pedal. A lot of pros use them and they're not much more than the stock pedals.