I have had my MAC setup for about 4 months now and have always noticed the tips... they are not centered in the holes in the facio, at all! They are almost not even in there at all.
The one I got wasn't centered either. I brought it back to the shop that installed it and after one adjustment, they said there wasn't much more they could do to center them. In the end, I bought 3.5" tips from Summitracing.com and had them welded on. I didn't like the wussy looking 2.5" tips and this was also a way to get the things centered under the bumper cutouts.
I had a similar prob with my flowmasters. I know I have a '98 and they dont have cutouts on the bumper, but, my tips were touching the bumper. I got some washers from ACE hardware and put them on the hanger to lower the tips.