How about the Engineers decision to put RIGHT ON THE DASH premium fuel ONLY. Then again in the gas door for the slower people, guess you missed that one too
. He then went as far as to dictate that the 87 was only to be used if you could not find 91+ (ie if your s.o.l. somewhere and all there is is 87, aka emergencey). By no means was it completely designed to take 87, because it can run on it in an EMERGENCY situation with your timing curve screwed to kingdom come does not mean it should be run on it. If you pussy foot the car around on 87 it wont kill the engine and the timing can compensate. But if you bought a GSR to drive like a grandma and obsess over mpg's then you have made a terrible choice and bought the wrong car. A GSR is meant to be driven, and that means taking up in the rpm's, where 87 octane and a maxed out timing curve are bad bad ju-ju for that poor engine. You may have grannied around on 87, but for the normal person who DRIVES a GSR its a bad decision. That knock sensor that is retarding your timing so you can run 87 doesnt work above 4500 rpms, because the noise from the engine would read a false knock. You see above 4500rpms the engine produces the same amplitude and frequency of knocking. So if you actually DRIVE that GSR on 87 your going to knock up high where your timing isnt properly compensated.