[Roush #1]

Garry,

I assume the 11:1 compression ratio you mention is the static ratio. If it is, you are on the cusp of detonation with aluminum heads.

However, if your dynamic ratio is down to about 8.5:1 with this set-up, I think you will be O.K., but it is really close.

Raising the octane a bit is probably the cheapest alternative to your delima.

J