The OEM twin disc SM calipers work great, IMO, when properly set up. I suggest that your customer focus on a DOT 4 fluid change/bleed, new EBC pads, & ensure that the OEM rotors are in spec & deglazed. Really.
I agree, I think the best upgrade would be floating rotors if they are still available since the ones Triumph used on the older bikes tended to warp but not as much on the SM as the BA. Probably less heat generated on the SM due to increased surface area.
I learned all I need to know about life by killing smart people and eating their brains. Eat right ,Exercise ,Stay fit, Die Anyway!
