Not wanting to take this any further off topic, but that photo concerns me Robin - are those your seats?
Bucket seats such as those shown here are rarely strong enough to actually take harnesses through the cut-outs, they are purely cosmetic. It was the same story on the old RS Focus - people we putting harnesses through the seats, but the backs of the seat aren't designed to take the load from a harness and can buckle and distort in a heavy impact, offering little or no support and potentially fatal consquences as the seat collapses around you. Just thought I'd let you know in case you weren't already aware of the dangers. The seat backs are separate from the base and arent stiff enough, like proper one-piece bucket seats, to handle forces exerted on them.
I don't mean to preach, but it's quite a serious safety concern - particularly on a track. They look lovely though... I hope I can source some.