If you're worried about detonation, run water injection instead of doing all the machine work on the combustion chambers. I agree with Twisted 6 that you should mill the head, not the block to get the compression you want. With 9.3:1, you should be able to run unleaded regular with a water injection setup. They are currently available from Coolingmist for about $300 for a normally aspirated engine, and they REALLY work. I've used water injection on one motor with 11:1 compression, and it took all the knocks and pings out, but I did run premium unleaded with that high a compression ratio. If you want to check it out, log on to
www.coolingmist.com for more info.
