Quote Originally Posted by falcongt View Post
Really? hhhmmmm Hes not going to like having to shell out more per gal but if it saves on repairs then so be it. What exactly does it do to the engine? Just curious. I know higher compression engines rewuire higher octane but wonder why the super charger changes what fuel you must use.
If you calculate the equivalent compression ratio it'd be even higher than the same engine designed for 91 octane with no boost.

In this case, the top piston rings are set pretty tight, and will expand chipping the piston. From there, it could damage the valves or the piston further.

Keep in mind a grand prix that old might require all of the usual 10 year old car components. Like any suspension bits or brakes.

Coolant will be well past its expiration date and will be chewing on those plastic LIM gaskets. Keep an eye on the coolant levels, if it gets lower and you can't see any leaks, it's probably the LIM gaskets. Down there it'll cost you ~$200 in parts and a weekend of time if you're newer to repairs like this. Good bonding opportunity?