I know most aftermarket exhaust system do not make power on an S2000, or you even loose power, but i would like to see some dynos with a HKS Dual, anyone?

 

Don't have any dyno results to show, but having the system myself I am extreamly happy about it! Sound is just fenominal , at high rpm its addictive.
Just make sure to de-cat it also
De-cat made a difference in my perspective.

 

Over all the years, it was always said that the HKS lost power, but I NEVER saw a dyno backing up this claim. It will be negligible either way, and you'll notice a bigger difference in power dependent on the weather from day to day, enjoy the sound and dont worry about it!