My roommate has a boosted S2000 and I have driven it plenty of times all motor and boosted. Its a great all around car, power is enough for all motor and handling is amazing. Top down in the blazing heat can be harsh sometimes. Gas mileage is great on freeway. I drove his car in a long distance drive and was able to pull out 31 MPG boosted.

As for all motor. If you get the Greddy e-manage ultimate, there is a tuner name Giles who comes down about twice a year to tune S2000's specifically. You'll be able to pull out about 10WHP but a lot of torque with just a stock motor.