340 Static Compression Numbers and Test Procedure

If you're getting detonation at 2500 rpm, 28-30* then quicker won't work.
Back to figuring out what's going on in there.

Locking out.
Sometimes its done.
Disadvantages are usually in getting good idle, and with a high revving engine, there can be timing 'lost' at the high rpms. (racing high, not street high)