The water trap is the fitting right in the center of the bowl on the bottom of the carb. It will have a 6 or so inches of fuel line attached to it with a plug in the end. That water trap will come off with a 17mm wrench. Get your 1/4" drive ratchet with a deep well 6mm socket. You'll see the brass jet in there so you can line it up. When the jet comes out, be very careful because there is a brass washer underneath it. Sometimes it comes off with the jet, but other times it sticks in the carb. If it is stuck, tap the carb on you palm a few times and it should fall right in your hand. The jet size should be stamped either on the side, or the end of the jet.
You better change the jetting before you run it with the SLP pipe. That pipe might call for a jet 3 or 4 sizes richer. You could burn it down if you don't rejet first.