Don't quote me on this, but I've had my car re-tuned for 98 and my tuner said I could happily run 95 as the ECU still retained its knock correction, so I'd say it would be the same case for your car, it would just advance timing within it's limits.
If you could afford the trip to Chch, I'd highly highly recommend @SAS for your tuning. In fact, give them a message on Facebook and/or @gotasuby. They'll be more than happy to help.