The exhaust system is now complete pending arrival of one extra 45 degree bend and some heavy duty clamps for the overlap joints.
The left system is constructed the same as the right except that the bend which angles the exhaust inwards and down is a 60 degree angle rather than 45 as the cylinders on this side of the engine are further to the rear of the engine. For final assembly I'll use a jointing paste on the overlap joints.
With the exhaust complete, I used the extra time today to cut out the oil filler door flap from the upper cowl. The removed section was riveted to a section of hinge and this and some stainless steel strip was riveted to the cowl to mount the door and provide a lip for it to sit on. A hole was then drilled through the door and the strip and a catch installed. I still need to fibreglass the strips onto the cowl to provide extra support and get rid of any gaps.