HP loss with age is usually due to loss of compression and/or degradation in ignition performance and/or degradation in fuel system performance. If you can confirm compression and leak down and you can keep the performance of the other 2 factors at peak, there is no reason that the engine's output would be any different than a new car.
Now, getting that power to the ground on an old car is another story. That's where things like clutch, tranny and other downstream driveline components come in.

 

Excellent thanks again.

 

Here are some high mileage cars I have owned, all bought used and sold running good:

1987 CRX Si - 146,000
1991 Civic DX hatch - 230,000
1986 Toyota Corolla - 190,000
1990 Acura Intega LX - 170,000
1990 CRX Si - 150,000
1991 CRX - 180,000
1995 Toyota Camry - 165,000 (current daily driver and still rockin)

My S is not high mileage yet, but I have no doubt that the S will have great durability.

Mile on boys and girls.

 

Just hit 137k (but only 20k on the new engine)

 

rolled 140k this week

 

Keep peddlin' ... I have 147K+ presently

 

I am now at 97K....but the motor has been replaced with one out of another '01 that only has 22K on the clock. New clutch too!!

 

What happened?

 

Dropped a valve into cylinder #1.

Yeah, I am very broke right now.

 

Keep in mind though that although the S2000 is capable of 100k miles easily and reliably, time has an effect. I know it's gonna be an awful lot to ask my 06 S2000 to go 100k miles trouble free when I'm only driving it about 5-6k miles per year. Time will catch up slowly, as age has just as much an effect on a car as miles. When you drive any car daily and often, it can be veryreliable and long lasting if properly treated and maintained. When you don't drive a lot, I found in my experience that you are more vulnerable to problems before 100k miles.
For those who put 15-20k miles a year or more on their S2000, You shouldn't have any major issues. A constantly running car for the most part is a reliable car.