Sorry if this has been answered a million times but am I better off with a PC III or V on my 08 SD? Are there any features on the V that make it worth while the retro fitting? This was the info I received from them...

Thank for your inquiry and interest in our products. The PC V was released for 09 models forward only.  We still have not tested and verified operation of the unit on many of the older model bikes at this point, so we cannot officially support it for use on anything other than 09 and newer model year bikes on which it has been thoroughly tested.  Many of our dealers and individuals as well have successfully retro fitted the PC V to older model bikes that have not changed from previous model years to 09. Since we have not done any testing on the older models we do not have any pre developed maps for any model years prior to 09 either. It would be extremely difficult to obtain all the older models and remap them so we  have now incorporated a utility in the PCV software to be able to import  PCIII USB maps and convert them to the PCV format to accommodate customers such as yourself that wish to use the  PCV on an older model bike.  If you have any other questions please let us know.

My answer is buy neither.

Tune ECU is the way forward, check the sticky section.

I would agree with Dan. He's not called super for nothing.