XR 200 exhaust modification

I was looking at the girlfriends xr the other day and would like to see if I can get the exhaust to be more free-flowing cheaply. I have already removed the baffle and installed a Uni filter. I have read that on the stock KDX double-walled pipe, that you could cut it open and remove the inner layer, effectively "opening it up" a little and gaining a little performance. Although I realize that a two stroke pipe differs greatly from a 4 stroke, would this same procedure be worth trying on the stock xr exhaust? Would I gain anything other than noise? I dont want to have the exhaust note unbearable, and I certainly dont want to lose the bottom end that makes this bike so rideable. I would love to come across a used aftermarket pipe for this bike but have had no luck so far and I dont want to drop $250 for a new pipe. Any ideas, suggestions for this bike?

p.s. I have already relieved any welds, etc., on the pipe.