Interesting to read all of this.  About 25 years ago I had a flat which had electric UFH - similar sort of system but electrical cables buried in the screed rather than pipes.  The down-side I found was the thermal lag from heating up all that concrete.  If the weather suddenly got cold outside it was the best part of a day before the room temperature recovered, so another source of instant heat was required for the interim. If it became warmer again so that less heating was required,  it took a similarly long time for the internal heat to drop back to normal and there was nothing you could do but open windows which is not good for efficiency.   The flat did have double-glazing but obviously better wall insulation would lessen the effect somewhat. 

Yes, it puzzled me last season, when my diff is 3.89:1.     I'm going to install (re-install) a lambda sensor.     Trying that will show. John

Are you able to check this with a wideband, or a couple of pulls on a rolling road should be able to determine this as they will have a lambda?  Seems odd you're unable to hit 100mph, even with what I assume is a short ratio diff.  

Thank you, Phil!   He's not a trader I've used before, so good =to have your comments. John 

This Phil. And the internal walls are probably mostly brick made from local clay. Which has a relatively high iron content in this part of the world. My house in Glasgow is 1850s and has similar wireless issues. My solution is to use repeaters that do most of the transmission vertically where the signal only has to go through the plaster and timber floors.

Should not be an issue .  I don’t actually know how stringent the rules are at track dsys/hill climbs , I need to look it up . 

I thought it was, but didn't want to embarrass myself in case my memory was failing 🤣 Interesting that you have had more success than me, I do wonder if that is related to property type maybe? I'm in an old early 18th century manse that is a) pretty large, and b) has a lot of sandstone walls throughout that do quite an effective job in blocking wireless signals of most kinds? I never get more than 12 months out of batteries, and often no more than 9. My system is out of warranty, but it works and I haven't found a comparable one yet!

Yes , the 6” one shown is hence why we are going to do a 4” version tucked further in . 

Looking awesome!    Stupid question probably but is that exhaust going to sit further out than the outside of the wheels?

"I run this in my house (and I recall there is another forum member here using it?)." thats me. probably had ours for about 10 years and its been very reliable, have only had one HR92 valve fail to work and got that replaced under warranty. Batteries last about 14~18 months depending on how much control they do. I now change them all once a year. You do get plenty of warnings when the battery voltage starts to drop.  Agree excellent system and does mean we just heat the part of the house we are using at the time. mike