it is so simple....that a lot of people dont even want to waste their time by ansering your question. i do not know for sure that the si exhaust would fit but i would assume so.

jack up the car....use jack stands....get as high as possible. there are two bolts that hold on the muffler section to the mid section. loosen those two bolts....if you break one...who cares....buy new ones. stainless steel bolts will help ease of installation further down the road but not required. use 5w30 on the rubber hangers and grab a pry bar and start yanking. those are normally on there pretty good. that is it.......look at your flange (flange is where the two pipes meet) and if there is a gasket there...and looks beat up...replace it. any parts store should have it if they dont...ten get one from anoter car that closly ressambles the size and or shape.