This is about the best I could do at night shining a torch through the exhaust . Only two ports can be seen but there's a third hidden off to the right. The first Special had two exhaust ports like other TeeDees and their normal porting, the main change being a switch to a wrist pin and alloy rod. The Mk2 has the same piston/wristpin and rod but a single exhaust of smaller total area to fit the 3 transfer ports in the cylinder.