If your car has knock-sensors, they will signal the PCM/ECU to retard the timing if detonation is detected, regardless of whether or not you have a chip. I have run 87 octane fuel plenty of times in the SHO, and never heard a knock or experienced any performance lag.
Most of the readily available "plug and play" chips do more than just advance the base timing. They alter the entire timing curve, so your timing will be different at idle vs. at WOT @5500 rpm. Of course, it depends on the individual programming too. The chip is just the medium, the programming is what determines performance.
Most of the readily available "plug and play" chips do more than just advance the base timing. They alter the entire timing curve, so your timing will be different at idle vs. at WOT @5500 rpm. Of course, it depends on the individual programming too. The chip is just the medium, the programming is what determines performance.