7A-FE Compression Ratio, Looking at changing the CR of my 7afe when I rebuild. Options

[PaukST]

Hey all, I'm trying to decide what to do with my 7AFE (have to take it apart due to a rod knock anyway). I've kicked around a few ideas (or maybe a lot ), and I'm currently researching what an increase in compression ratio might do. Does anyone have any info on this? I'm unsure of the potential difference in performance, and I can't seem to find any hard data on what pistons (4age, smallport 4age, 4agze) result in what CR. I've been trying to make sense of these tools and formulas - http://www.csgnetwork.com/compcalc.html http://s-86.com/s-cr.html and http://s-86.com/s-cr-chart.html - but I'm having a hard time digging out the relevant numbers. Doing the math myself or using the calculator I come up with significantly different numbers than their little handy chart, so I don't know what to think. Is this a futile exercise? Will I even be able to notice a performance difference over the stock 9.5:1 without having to use higher octane?

[PaukST]

It looks like reducing the chamber height by ~ .5mm would put me near 10:1.

If I need to get the block/head decked, I might get it taken down by .3 or .4mm instead of a minimum amount. Taking it down by .3mm would give me a 9.76:1, or .4mm would take it to 9.85:1 (assuming correct math). If I'm already going to get it decked, I doubt I'd run much risk at either of those levels (and it leaves room for error if my math is bad ).

If I don't need to get it decked, though, it's a stock rebuild for me!