I tried one run where we removed the intake filer completely. That resulted in no benefit.
159 horsepower to the rear wheels is pretty low. We usually see a 15% loss from the engine to the dyno, so we'd expect 170 rear-wheel horsepower from a 200-hp-rated car. 159 at the wheels would indicate more like 187 at the engine. Perhaps the power will go up after the car has been run in some more. We'll check back.
The modest result on the dyno brings to mind our current vanity plate for the car, pictured at right. (Vanity plates cost next to nothing in Virginia, so we'll probably end up changing these a few times.)
We got some decent video footage of the dyno runs with the muffler on:
I also did a little bit of outside recording of the sound with the muffler delete installed. To my surprise, the noise was pretty moderate -- I wouldn't really mind living with that on a daily basis. Although there's no increase in horsepower, taking off the muffler does drop about 25 pounds from the car -- almost 1% - so that's a plus. We haven't decided yet if we're going to mass-produce the muffler delete. Let us know if you'd be interested in purchasing one.