Adding weight, but don't want a big wheelie....

So, I have a 10.5 index race coming up in about a week and a half and I need to slow the car down. I'm currently spot dropping at the 1000' mark and it's still too quick (darn cool air, lol). I have the ability to safely add weight in my trunk, but I'm a little worried about putting the car on the bumper. The car currently pulls the front wheels about 12-14 inches on launch, which is fine, no drama....my question is, will adding another 100-150lbs to the trunk put this on the bumper? I'm just a little nervous about hurting my car.

Any experience with adding weight would be appreciated.