Hi Mark, A lot of people prefer them, especially if the actual metal frame of your seats has gone the way of the dodo. I haven't done the conversion - but the rails of the seats do need some basic reshaping to fit into the Spit/GT6 tub. However, it might still be worth revamping your existing seats (especially if the frames and your covers are still serviceable) have you tried Park Lane Classics? Owen is a top chap and makes all of the foams himself. I just reupholstered my GT6's seats myself as a Christmas present to myself and got new covers from him at the same time (decidedly unoriginal spec leather but to the exact same pattern) and as you can see them next to each other it gives the original seats a whole new lease of life! Good luck with whatever you decide but plenty of people here have made the move to MX5 seats. Cheers, Dicky