I've never heard if a system that switches back to petrol at 6.5krpm, I kicked the shit out of my old V6 some days and it was always on gas, right through the rev range, nice and smooth,
Also most modern systems can start straight on gas, my old one used to run on petrol for the first 5 minutes of every day, after that the car automatically started on gas, but if left overnight it would auto start on petrol again, apparently it was a safety feature to check for any leaks and a pressure test,
There was a company in Glasgow quoted me £1400 and needed the car 2 days to do the conversion, that was fully fitted etc with the certificate, make sure you get the certificate! Lol
Sent Using The Force.......