i have already done this as i know the p100 is around 200kg more and still have more bits to cut out
as for the lag
if the engine can build its revs faster (ie with the help of a lighter flywheel) this means it will get to the point when the turbo comes in faster so surly this can only make it better
as for anti lag i have read up abit on it and i have seen too many cons so i dont really want to use it