But in this situation, using the the comptech FPR, the intercooler with a 3.8 pulley makes more power than the aftercooler with the 4.0 pulley.

But of course with engine management and injectors, it will be better to have as much boost as possible.
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Correct.

You can compensate with a smaller pulley to regain some of the boost loss, but when you get to the smallest pulley you have no where left to go but make what you have most efficient. and the fmic is not efficient for making the most power at the limit of what the blower can spin. There is only .5psi loss with an A/C. Average per psi is 15whp. Average hp gained from 10 degrees cooler IAT I believe is 3hp average. fmic at max efficiency gives you about 30 degrees cooler temp on average over the A/C. Average boost loss with an fmic is 3psi.

A/C = +3psi = 45whp

fmic = 30 degree cooler IAT = +9whp

Which is the better way to go?

 

Tell that to pro charger

 

This story may provide some comfort for you and it shows what excellent detonation resistance the S2000 combustion chamber has. I bought a used S2000 with an aftercooled Comptech kit. The previous owner had driven it 2 years with the SC before I bought it. He never installed a boost or AF gauge. I immediately instrumented the car and found the FMU produced ZERO fuel pressure gain - it had been hooked up backwards. AF ratios exceeded 16. I think the motor survived without damage because it was so lean it couldn't develop enough cylinder pressure to do damage. If it was richer and closer to stochiometric damage would have been more likely in my opinion.

BTW, its running great now with a 3 inch pulley, 5th injector and meth/H2O injection.

 

I can attest to that^^^