I don't want to get too much into this because I know what I am saying contradicts popular belief here on tt.net. I have equipment that lets me listen to the knock sensor so I can pick up very low levels of knock, and from tuning my car I believe JWT's timing map is only safe upto 14-15PSI on 93 octane. I believe you will get low levels of knock (undetectable w/o the proper equipment) above that which will slowly kill the engine. You can run higher boost, the chip/timing just needs to be tuned lower for it.