I dunno about your 88, but my 86 with the B230f engine had from the factory, 9.5:1 compression. that is rather high to be running the cheap gas on. the ignition control unit may be able to sence detination via the knock sensor and retard the timing to prevent detonation, but when the timing is retarded, power and efficientcy will suffer. I am the second owner of my 86 and it has 330,000 miles on the original engine and has always had top grade fuel, I say if it aid broke don't fix it... Oh yeah not to mention that both the manual and the car havve warnings on them that less than 91 octane can be harmful to engine life.