Focus resonator box

You really are a berk aren't you?

You really are a berk aren't you?

Helpful.

I don't have a Focus so I can't tell if it leaves a hole in the side of the air box which will let the engine suck hot air from the engine bay instead of cooler air from outside.

It won't make an easily perceptible reduction in performance on a fairly ordinary car and I doubt you would notice the reduction in fuel economy. Moreso on something turbocharged I guess.

Methinks that only people who think it's going faster because it's noisier sooner will perceive it's faster.