A lot of people have been looking for performance pipes for the ET2, and there don't seem to be any options that won't hit the bodywork the first time you go over a bump.
I spoke to someone who told me that in Europe they are installed by putting a 120/90-10 rear tire on, then getting the longer shock that has adjustable damping and adjusting it stiffly.
The Malossi pipe 3216692 for the LT50 bolts right on, and there is enough clearance with those changes.
The Malossi longer rear shock is 4615432.