The issue with modding a standard 98 is that it lacks the hole through which the new power tube feeds the loader with air which is moving the arms in the feed system giving it the 15 bps feed speed. If you look to the pic on the right you see the marker with no hole. Custom and Pro versions of Tippmann 98 have it so if you are an owner of Pro or Custom skip this reading. You will need a drill, the marker is made of aluminum so simple all purpose drill bits will do the trick nicely.

On the left see my handi work... it might be dificult to determine where to drill exactly, I just alligned the powertube and avreaged out where to drill, used small drill, tried the tube, drilled bigger, and corrected and driled again with bigger drill. After you make that hole this also opens a way for you to have a response trigger so its a good mod anyway you look at it.