hi ive run 2 lexus gs 300 mk2 98 and2001 models that's the straight six,the only gs 300 the 2005/11 mk3 now that's difficult to get lpg fitted too.for reasons unknown to me,but give the lexus club forum a little while and we will both have that answer, so straight six no probs/v6 probs.i would highly recommend the lpg conversion saves you a lot of money in tax and fuel costs roughly half of petrol.but get it fitted by a good company and get the certificate,after fitting,or you've wasted time and money,brian