LPG Conversion to Toyota V6 4Runner

I've been running LPG in my Patrol for over 7 years and have had one backfire in that time, luckily it didn't destroy the air flow sensor. I'm fortunate enough to work next door to a very good LPG installer here in Melbourne and he sees lots of dodgy installs performed by other LPG fitters. With the government grant it appears that things are getting worse with these fly by nighters getting their LPG licence and doing as much work as possible to get the $ in but b#gger the quality. It has got to the stage now that components are in short supply and the dodgy fitters will just fit what they can get regardless of its suitability.
As for backfires, Mike next door explained to me that adequate spark is probably the single biggest prevention of a backfire. When he installs LPG he recommends new plugs, new leads and a check of the coil and distributor. He uses Eagle leads as he's never had a problem with them, he won't touch Top Gun, Bosch or any of the no name brands. As for plugs he uses either Denso or NGK standard type plugs,not these "U Beaut" multi electrode ot the "next best thing since sliced bread" types. He doesn't recommend platinum plugs, he would much rather see the plugs changed every 40K as it's good insurance against a backfire.
He's done lots of Yota V6's in either Hilux's or Prado's and doesn't see they are any more difficult to do than any other install.
Regards Andrew.