If I remember right, running 6psi @ 10:1 compression produce near same horsepower running 9psi @ 8.5:1 ratio. Not too sure. (forgot the calculation... but I prefer high compression anyway
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At least I have better power curve from 1k to 4k rpm on city streeet.
No matter it is higher or lower compression engine, you want to tune it right to make sure detonation doesn't happen.
Most people can't get the FS-ZE running right is because of the engine management. It is hard to get the FS-ZE running correctly without the original MAF, and ECU from stock engine. Go stand alone is too expensive and not logically economy correct.
an FS-03 will make more power at lower costs.
Not really. Stock FS-ZE is making more horsepower in n/a is because of better manifold design, higher-rev, valve, etc etc. Since most stock engine can handle 8-9psi without problem, I assume FS-ZE too. To evenout the horsepower, you need your FS03 to be running at 11-12psi. At that point, you need to upgrade your rod and piston on FS03 if you going for anything higher than 9psi. Parts dont' come cheap, so I guess the price will run near the same.