I've found that when you're using a hole saw to cut through sheet metal, it's usually better to go slower RPM with a lot of force than to use the highest setting, as you can keep better control, and can back off right away if the bit starts to snag, which can result in a hell of a tweaked arm. And if you're planning to drill through stainless, going slow with a lot of force is the only way to even drill the hole, as going fast will heat-temper the stainless, and then you'll never get through it with a drill. BTW, if you're using a cordless drill (I drilled many holes in stainless with an 18v dewalt), just make sure to let the drill rest adaquetly between holes, or you're gonna burn out the motor. This applies to any drill really, but cordless ones seem to burn up alot faster...