You really want to change the front axles for a titanium set from CRC. The original HB axles break real easy. I owned a HB C12 and the first pack I ran the front axles broke. If you do so, you will also need a set of steering blocks from AE/CRC or the delrin pieces from CRC.
Also if you want to use the JACO Prism rear wheels, a different rear axle is recommended. I used a RC12L4 axle which is from IRS but you can also use any other graphite adjustable rear axle. This will really be an improvement because JACO prism wheels are almost the most used wheels in the Netherlands and these wheels have a -3mm. off-set.
Broken front axles...
@HB: Als je verder nog tips en dergelijke nodig hebt stuur je me maar een PM ;-)