ok, thanks for all the replies. Really tempted to do this but need to check on how much it would cost me. I would hope to do most of it myself but obviously a fair bit of it would need to be done elsewhere such as a remap, balancing flywheel etc and the headwork.
How much difference would it make to have the flywheel and crank lightened and balanced compared to without and how much would I be looking at to have it done?