I've never bothered with hardened valve seats, never had problems as a result.

I wonder if that's Skoda design or if the "need" for engine modifications was shell/esso etc's ploy to keep us buying lead?! (Apologies for the conspiracy theory, lol).

There are lead replacement addatives that you can put into your tank to stop this pinking if your car was designed to run with lead. Millers do one called VSP Plus and there is Castrol Valvemaster Plus. These not only protect valve seats but also increases the octane. Remember normal Unleaded has a lower Octane No than Leaded had (Ul = 95 vs Leaded = 97).

When I ran an old Metro, I used the Miller's stuff, but it was quite expensive as you added a full bottle to 40l of Ul. I used to put half a bottle to 20l.

You lot are going to end up in white lab coats with a dozen pens in the top pocket.

Several of my friends actually are scientists, and part of my job is repeatable software testing.