My old man has been running his cars on LPG since the stoneage, all been 6-8 cylinder, now looking at a v10 I used to have a van on LPG, & a friend of mine runs his motor yacht on it, running two 6ltr V8s never had any major problems, just the odd filter every year, they do tend to knock out spark plugs 40% faster but that's no hardship really.
Not much space for a tank in an s2k though.