Stopping the knock: Lower compression and ported heads...

Those gaskets also require a retorque after the first heat cycle..

That would be a pain in the ***. I'd have to pull the headers to gain access to the lower row of head bolts! That alone would be enough to deter me.

Regarding the advise to NOT use the steel shim style with aluminum heads, I have heard that. I've also heard/read from others that claim to have done it with no problems. May not be worth the risk though, just to save a few bucks.