We did do some dyno experimentation at the 10th annual IDI Weekend, and we firmly concluded that 8.0 to 9.5 was the sweet spot for timing. Any more or any less, and you loose power. This was with standard #2 diesel fuel and no additives, at 80 degrees air temp on a Dynomax wheel. While each IDI may be slightly difference, the fuel and the physics are the same for all, so I doubt any significant variance would be found, assuming the pump and injectors are in spec.