I'll throw my two cents in here I guess.
1. Remington Sluggers are excellent slugs.
2. $9.00 for 15 is a great price.
3. I would say considering the time, money and testing that goes into factory ammunition plus the flight charecteristics of a slug round itself as explained above by "oli700", you would do yourself a disservice by modifying the projectile.
Chances are that because you would be unable to drill the hole perfectly in the middle, you would get instead of a stable flight, a projectile that would start to tumble soon after leaving the barrel and the top of the slug wouldn't even be the part that hit your target first to give you the ripping-shredding effect you wanted to begin with. Which again would be just the opposit of what you wanted to accomplish by drilling the slug.
The proper term when a typical slug turns sideways in flight and the hole it leaves as it strikes the target is generally known as "Keyhole."
But like I said. That's just my two cents worth and the only way you would know for sure is through rigorous testing. If you wanted hollow point performance, maybe you should consider something like the Federal Power-Shok 2-3/4" 1 Ounce Sabot Hollow Point Slug. But anything that has the word "Sabot" in it is going to be costly. Never less that $1.00 per shot and for some of the premium ammunition we are of course talking about can be $3.00 or more a round.
Paul