This is probably better addressed by Spud at FIE but I'll throw in my experience here though I run a BBC. The static compression vs dynamic compression is affected by cam duration (intake closing point), cylinder heads, etc, how it breathes. 10% should not be an issue, at 33%+ things start changing. I have found that each 10% is worth about .1 seconds. I only have experience up to 42%/methanol not M-5, 33% was the same tuneup as methanol. I started a couple of steps fat and a couple degrees retarded on timing and ultimately came back up to my original tuneup for my combination. My suggestion is to read Spuds Nitro Notes on his web site, buy a hydrometer and talk to Spud . Also as you add more nitro you make more torque so you will have to deal with that maybe. If you start down this path you won't want to go back.
Mark S
