Not a clue about the balancer...but I can say I found the stock HID headlights on my '09 disappointing. No better than the halogen lights I had on another car. I wouldn't suggest you spend much to replace the stock non HID lights.
Essentially, it's a test procedure that shows the part has been tested under certain conditions and passed the requirements set up by the specification. The 18.1 spec shows that it has to spin at 12,500-13,500rpm for an hour without failure. SFI has many other specs covering just about every car part used in racing.
The harmonic balancer (damper) for an '08/'09 Bullitt is different than a regular GT of the same years. It was changed as part of their effort to increase the redline from 6250 to 6500. I believe the '10 GT also used the larger balancer. Most if not all aftermarket dampers are shown as '05-'10 replacements and don't acknowledge the original size difference.
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