I exported the.csv, as suggested and compared speeds.
Although I calculated ratios from 1.4_ up to 1.9_ , I believe this was due to not having enough road to hold a steady speed for more than a brief time. Averaging a number of results, I obtained a figure of 1.6.

This was very close to the figure ...

Thank you kindly, sir.
I was pretty sure there was something already there, just needed your expertise.
I shall post back my results asap.

Sorry for such a long post but I wish to explain my investigations, thus far.

Initially, Laptimer (and it's video recordings) displayed speed readings almost identical to those shown on my headunit's display (Kenwood DNX7240BT, with Garmin sat-nav.) Despite slight lags, during acceleration, my ...

To the OP, Harry & those considering same ;

I was going to request the addition of TPMS info., too. I'm glad not to have bothered Harry, in hindsight.

Using the tyre-valve type of sensors, I have bought and binned two complete systems, with no less than 10 wheel sensors destroyed in under two ...

I wasn't able to get my BT1 working with HLT using RoqyBT4.
Problem is completely solved now . . . as I have installed the fantastic v.16 !

I updated to v.16 yesterday afternoon.
Some tasty improvements, especially for a recent Gopoint BT1 owner !

Looking forward to next month's trackday (Trax@Silverstone) even more now.

Cheers Harry and well done.

Andy

I recently bought mine for less than that (delivered to England.) This was copied from my Paypal receipt ;

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BT1 by GoPoint Technology
Item Number BT1 $59.99 USD 1 $59.99 USD
Subtotal $59.99 USD
Postage and packaging $37 ...