Fair enough; I have said what I have done and it is a matter for you to decide. As I understand it the factory setting is an average designed to allow the use of fuels of different grades and that it is possible to extract more performance by advancing the ignition slightly if using premium grade fuel. Also, the fuel available in 1996 (when my RS was made) is different to that we can buy now as it didn't contain ethanol and, as my RS doesn't have a cat, I could run it on leaded fuel (if I could get it). I am therefore quite relaxed about adjusting the timing empirically. I can determine engine temperature from the RID and anyway I doubt that, if care is taken in aligning the plate to the marks made, the timing is likely to differ by much more than 1 degree. I am therefore happy to take the risk. As they say, yer pays yer money and takes yer choice.