There are several little tricks for getting it just right. One that is pretty cool is to set your bike on stands. Remove the fairings. remove one of the motor mount bolts were the slider will install. Set a laser pointer several feet away on a tripod and aim it dead center at the hole. Put the bodywork back on without disturbing the bike. where the laser is pointing on the fairing, is your hole center. You can now remove the fairing again, or depending on the bike, finish the job with the fairing on. Make a pilot hole where indicated by the laser beam, and use a 1 7/8" hole cutter (or other size depending on your brand of slider) to cut the hole. Put a piece of medium to fine grit sandpaper around your slider, and smooth the cut edge. You can black out the cut with a Sharpie pen. Repeat for the other side.