[Swissracer]

Judging by the vast difference in design between their analogue and digital cars I fail to see how they can become compatable with just a chip, especially when so many folk stated the gargantuan guide blade was a requirement for Carrera Digital.
I wouldn't hold your breath for any makers cars made before Pro X being compatable and suggest the spare chip is for repair only.

As far as I understand it the ONLY digital system capable (so far) of backwards compatability is the Scalextric system.

 

[Swissracer]

I stand by my post above, but will be happy to be proved wrong. However, even without the chip no non pro x cars run on pro x track system and pro x cars do not run on analogue so how will just changing the chip help?

I am going to try a conversion tomorrow as we have some pro x cars at the track.
IF I can do it without damaging the pro x car (they belong to thomas) I will post the results here, however I would like to clarify one point made above...

QUOTE But then changing a guide flag is standard practice in the slot kingdom.

I think you will find this is ONLY common practice when changing from a standard guide to a superior one, I cut my guides down in length and can not see me making them longer for anything.

Point taken about the lap counter issue though, I remember being told that now it has been repeated.