Upgrading the tacho

Hi,
The Tacho in my twincam works in normal driving but when you give the engine a real hard rev it tends to hesitate and is not that accurate when approaching the red stuff
. Has anyone had there tacho rebuilt with a new electronic one so it keeps the appearance as standard if so who is OK in Victoria? Or i there any ideas ... besides putting a secondary large taco on the A pillar.
cheers
The Tacho in my twincam works in normal driving but when you give the engine a real hard rev it tends to hesitate and is not that accurate when approaching the red stuff

cheers