HP and resonators

Do you guys think the factory resonator inherently loses horsepower, it's a pure 3 inch straight through design with the can around the outside of the pipe and the holes are drilled in the pipe only half way around it. Meaning it doesn't have internal holes allowing the exhaust pressure and sound waves into the resonator from a full 360 degree of the pipe, only about half.

I'm swapping out the straight pipe that came with the Ford Racing sport system and my stock resonator that I had cut to be the right length so I can test drive both with a fairly easy swap.

I'm just wondering if a stock resonator slows the exhaust evacuation at all
And robs any power?

Thanks

It is very, very doubtful in that the resonator would have any effect on horsepower. The primary source of backpressure in the exhaust system are the cats, and to a much, much lesser degree, the muffler. Compared to them, the resonator has no effect at all.

Thanks!