Before my problem above, my gears changed at exactly the marks on the speedo (|,||,|||) with the revs almost in the red. If yours are not slipping and change 'sharply', then I would say you may be able to get them to change a bit earlier by adjusting the bowden cable which lies between the transmission and the engine bay. Do a search on this forum for 'bowden cable' and you will get lots of info on this.