there's a dozen choices for the zzr for a slip on ranging in price from $200-$400. d&d would be the loudest and probably cheapest. yoshimura, muzzys, micron, fmf, viper,hindle, etc...... all make slip ons that will fit a zzr,but im not sure about the sound levels as they all vary a little, but all are decent as far as quality goes. as far as jetting it isnt required but at least shimming the stock needles is recommended. there are several threads on how to do that just do a search for shimming needles.
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