It think what he's asking is should he run a tank or two of high test before he installs the chip. Or just fill it up with high test and then install the chip. I don't believe it would hurt either way. The knock sensor would help the engine with the little bit of 89 left in the tank. Just make sure to run high test after the install, should be okay.
1995 325I, tinted windows, K&N, debaffled air box, BMW style #104 wheels, Nighthawk low beams, smoked side markers, smoked corners, smoked taillights, M3 style heated mirrors, various interior bits, Bosal cat-back