I went and ordered the HI-6S and harness all from Sumitt, cost $158.00 total. I've already got an MSD Blaster coil (pretty new) so I'm gonna use it. The guy at Sumitt said that the HI-6 is digital and for cars running at least 10:1, the HI-6S is analog and good for anything below 10:1...I'm at...