[Baldock]

Have you looked at the aluminium nozzle that allows you to further install an extra rubber (sometimes 2). Your 8mm shaft could possibly be to heavy for even three bands and so the 4th could add the extra power to build momentum of the shaft more effectively. ie. shoot it faster. This setup i have heard also works great with larger diameter shafts (10mm+) giving you the option of interchanging shaftes if you wish to do a spot of open water.