I've been riding my ZRX (and modding it) for 3 years now and I've never seen nor heard of such a thing. I'm sure the left side of the ZRX can't support a can on that side without a mod I haven't heard of. Why??
My brother bought a ZRX a couple weeks ago and he likes dual pipe exhaust. He really likes the exhaust on the Suzuki SVs. Just looking into it, seeing what's around.