by running a seperate cooling line to the pipe, youre not adding more cooling to the engine so it will not affect anything.. you will still have one line to the engine.. the purpose for a seperate line for the pipe is to get more pressure in the head pipe and more effectively tune your exhaust... run the cooling line to the bottom fitting on the pipe then get a tee with one end to a bypass with a restrictor and the other to a flow control valve... the key here is getting fresh cool water to the pipe so it can rapidly heat and cool for best all around power from low to top end.. having the cold water also allows the pipe to be dried out further without burning the coupler because the water is cooler.. the restrictor in the bypass line keeps pressure in the head pipe so the squirters will mist water instead of dribble.. also keeps pressure up to fine tune your flow control valve..
with the pipe a little drier you will heat the pipe up quicker for more rpms.. when you let off the gas, the flow control valve closes, cooling the pipe down again for the low end response you want when going around a bouy..the flow control valve keeps the water box dry down low for better response as well... it will take some time fine tuning but you will really notice the increase once you get it dialed in...im running a basic brass watervalve in the bypass line to fine tune my ski... keeping it setup this way will allow you to make changes in different water temps too...
i dont have an sxr but have a highly modded 550 with a pjs t-1 engine and a factory full pipe with the water screws.. im sure the screw settings will differ from your ski but this is just to get the idea.. i have the top screw open just under a 1/4 turn and the mid closed... after doing this to my boat and really noticing the difference, this should be standard on every ski running a factory wet pipe...its really cool making small changes between the head pipe screws, fcv, and the bypass restrictor and noticing big changes..