You measure it out to the equal length as a regular FMF shorty. After doing this you take it all apart and mark the length with black electric tape, or at least that's what i did. After this you should first cut the canister with a hand or electric saw. You can then cut the circular peice that runs through the center of the canister. It will have a hole bunch of holes in it so make sure not to cut it to fast or on the holes because it could cause the holes to crack thwough the whole pipe. By the way it's easy to avoid so don't worry about it. After this you can cut the packing and put it all back together. The only thing you need to do that may be unavailable is to Put these things called rivets in it. To do this you need drill small holes first at the three or four points on the silencer. Then you need to find the corresponding Drill bit that matches or is a teeny bit smaller than the rivet. You will then need a special type of pop rivet gun that u can load the extra rivets into and Just pop it in. Then you put it back together and you are done. This is much easier than you think so don't worry. And if you or your dad or whoever is familiar with tools it is a peice of cake. Just go for IT!!!!!!!!