Typical Car A/C takes up about 15~25 HP to run the compressor. The lost of power is more noticeable in cars with less HP as it represents a larger % of the overall HP and more noticeable in cars with less torque (like the S2000). If you turn on the A/C in a Z06 or Viper you won't even notice the loss of power but in the S2000 it's pretty noticeable. FI or NA does't mater much in the S2000 as most S/C don't produce much of a different torque or HP curve compared to stock and your still weak below 6000 RPM (unless you have the new Kraftwerks S/C or good turbo, then you won't notice any loss of power).

 

what's it matter if there's a loss of power as it was stated above AC kicks off when WOT.