You could have had mine, have had them for years but never fitted them. I am looking at putting in some classic two tone snail type horns that sound like a macho car :)
Make sure you seal the underside of the rivnuts with silicone, a major area of water ingress, mainly over the pollen filters. Put a dab on the new screws too, they sometimes split open, I replaced all of mine, I bought a big pack of black self...
I have mentioned many times that the plastic rivnuts for the self tappers (as per Keith) loose their foam seals and let copious amounts of water in. Just pop them out and dab silicone on the flange, when you put the screws back in give them a dab...
DId you read the manual?
https://lpgshop.co.uk/content/lpg-software/Prins%20General_installation_manual_Part_1_LPG_CNG_VSI-I_VSI-2.0_V2.0.pdf
They all usally work the same way. I found this on a forum about the BRC system...
For emergency LPG...
On my old RRC it did start but very reluctantly, however, it was not a multi point. The LPG installer I used when I had it fitted in the P38 in 2010 did actually manage to start on LPG (very rough start until warm) but I have no idea how he did...