Call it holy thread revival or what.. but I want to know what happened next!
Steve hasn't frequent the forum for some time now but I believe he still has this GD1.
However, the last time I met up with him at Croft for a track day back in 2014, he had black smoke coming out of his exhaust during the warm up lap so he didn't want to risk anything as he had an +6hr drive back home.
I don't think he ended up sorting that out as he couldn't replicate the problem on the road and as such didn't bother him too much.