Unmodded Powerbites won't fit on a 28T MDS. You need to grind down the arm so that it fits the curvature of the MDS guard. However, if you flip the MDS around backwards it fits fine since that side is flat. I haven't had the time to grind the arms down, so I flipped the MDS around backwards for the time being.

 Uh oh...I'm planning on getting a 28t MDS. I have hollow bites. I know the arm shape is slightly different. Do you know if it's compatible with hollows?

 Not sure. On a Powerbite the platform that the spindle boss is in goes up further and slops gradually. On a Hollowbite the platform is much shorter and slopes at a steeper angle. I assume they did this to make it more compatible with shorter sprockets. This should make it more likely that it'll be compatable, however I can't say for sure since I've never tried it. You might try asking around on BMX-F or something.

 It's a Pantera, not a Tierra.