Originally posted by DennyW
About 8.82:1 on 87 octane gas, so 9.1:1 should be ok on premium.

The rule of thumb for a "relatively stock" engine is about
9.5-10.0:1 on 93 octane (R+M/2 method).

The compression ratio you can get away with depends on a
great many factors...cam timing, intake/exhaust flow
quantity & quality, ignition timing, air/fuel ratio, operating
RPM, etc.
and squish