SVT recommends at least 91 octane because of the 10.25:1 CR (I think 10:1 for the earlier cars) so it isn't necessarily B&B that makes you need higher octane. The Duratec does have knock sensors that will back out timing if detonantion is detected (kills power) so you can usually get away w/ 89 but it isn't a good idea, especially w/ NOS.
sinep, you may wish to get a ID-10T chip to control detonation under NOS.
