I decided to remove the modern plastic vents or gills from the hull sides and replace them with sculpted or modelled plastic card gills. The vents were removed by placing a scalpel blade between the vents and the hull and twisting the blade - this did cause some damage, but this was quickly repaired with filler. I cut a strip of 4mm thick plastic card into a tapered or sharp triangle section and then sanded the cut edges smooth. Once I was happy with the profile I glued four gills to each side of the forward hull with superglue. When the glue was fully set, I used a scalpel and sanding sticks to refine the shape. I think the sculpted gills look better than the earlier grey plastic ones.