o.k i have some answers for you.Known fault and rectification for the clutch judder,there is a modified clutch plate and friction plate,all covered under manufactor warranty.There is allso a rectification for the gear change problems(namely 2nd and 3rd),a new lay shaft and bits and bobs for the gearbox.If you are having the clutch replaced might be worth saying you have issues with 2nd and 3rd gear change to get this new lay shaft fitted while you are there? Lexus wil not do these things as a matter of course,you have to say you have a problem and then the mods are carried out.Back to the 5th injector issue,only the 5th injector and engine e/c/u upgrade are carried out,Toyota are carrying out the tests and ground work with the modified injectors in there T180 range of cars ,if this proves to work then Lexus will follow.Hope that helps? You know what they say,its not what you know......its who!!!!