Just recieved my Wilwood 2.75" big bore calipers in today. These are very nice calipers, just like the Wilwood 2 inch metric calipers. The piston diameter measures 2.704 inches. On the underside of the caliper, there are ridges that bridge the piston side (inside) of the caliper to the wheel side (outside) of the caliper. These ridges are not present on any of the other calipers. These ridges should cut down of caliper deflection. The weight of each of the 2.75" calipers is 4 lbs 8.6 ounces with out the bleeder screw. I hope the 7/8" bore g-body manual brake master cylinder can handle the increase in volume these calipers may require.