At last I'm no longer top of the pops So a couple of shout outs and thanks for help on this forum - especially this thread: https://club8090.co.uk/forum/viewtopic.php?t=9137
Pickles for the NGK codes, Speleobod for the Champion codes (spares), Steve at Gasure for fixig the whole lot up so it switches back again from petrol (yay :7)
Since fitting the NGK plugs got from www.spark-plugs.co.uk the riiculous amounts of popping and backfiring have gone and she runs beautifully! I splashed out for the iridium ones and they're fantastic - definite difference in power, no popping, yet to see change in MPG...
Could the following info get added to the Wiki as recommended plugs:
Pickles wrote:Spark Plugs.co.uk who sell them they said try a grade cooler because of LPG causing localised higher temp and always use single point.
Also reduce gap by 0.2mm that would be 0.5 or . 020 on a 2.1 T25
they also said the Iridium tipped were better with LPG due to reduced
voltage required.
NGK Iridium Plug BPR7EIX ONE GRADE COOLER £6.99 each
NGK Ordinary Plug BP7ES ONE GRADE COOLER £1.91 each
Champion RN7YC £2.05 each
This is the biggest and one of the cheapest changes you can make to sort out LPG stright off, codes are v. useful
Thanks to all on these forums for the help.