Just taking out the insulation from the fat part of the standard pipe gives good results.
See the link below for the mods I've done to mine to get better low end power, including lowering the cylinder. I've just finished testing it with the spark timing advanced more. what a good difference. runs a little hotter but much more grunt. I just turned the stator plate clockwise one click. make sure you use antifreeze or else you'll boil off your radiator fluid.
All of the aftermarket pipes are made for the regular KDX which uses springs instead of bolts to connect at the pipe/cylinder junction. see my SR page to see how to convert an aftermarket pipe to work on a SR.
Let me know how your mods go.
rock on