The higher the compression ratio, the more power you'll get. You HAVE TO be careful with compression (and timing and fuel mixture) when you're doing power adders, otherwise it'll go up in smoke. Personally, I would stay around 9.2:1 or lower for power adders, and a good FMU. I don't have that much experience with them, but I'm sure our other members will tell you a little more than I can.
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Capri306, Moderator, The Mustang Works Online
1979 Mercury Capri, 5.0L -- C4 -- 2.73
1987 Mustang LX Notch 
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