[maxtheaxe]

Pins as a rule are either 3 degree or 5 degree taper, but it's hard to say whether they used any such standard on cheap MIC pins. I would think the first thing you want to do is determine which taper your guitar uses. Also, and this is just me personally, enlarging the pin holes in the guitar would be the last thing I would do, and then only if there was no other option.

If you mess up the pins, well...you're out $4.50 and your time, but if you go too far on the guitar itself, you're stuck with it, short of replacing the bridge.

Stewmac has properly tapered reamers for pin holes; I thought about getting one, but like many of their tools, they're hella expensive and I probably wouldn't want to go there anyway, for the reason already stated.

Good luck!