i'll be honest with you having expierience of VAG warrenty etc its not worth paper written on,plus im in northern ireland with only 1 lexus dealer located 65m from me who are a bunch of stuck up plonkers and ignored me when i went in and wanted a test drive as i was in loan car from audi garage while my a4 was being repaired yet again
volvo ,vauxhall,honda etc have no probs with the conversions or covering warrenty issues as long as the kit is pro fit and certified
i can't see a problem with it,lpg has an octaine rateing of 99 which is higher than super etc so its bound to be better for your engine.