Really, we promise, this is the last one of these teasers we’re going to post of the Roush Performance’s latest and greatest Mustang. First we saw the teaser pictures, then a behind-the-scenes of the photo shoot with two sets of chrome shoes. Now comes the latest teaser, a brief video clip of the Roush RS3 at the historic Laguna Seca race track. And boy does it sound good.

“RS3” certainly stands for “Roush Stage 3,” though the Livonia, Michigan-based company has been uncharacteristically tight-lipped about their newest flagship Mustang. At this point, anything less than 500 horsepower and we’ll be sorely disappointed, though with the new 5.0 liter V8 engine 500 horsepower shouldn’t be too difficult to achieve. Rumor has it that the RS3 will have at least 540 horsepower, 15 more than the upcoming, supercharged 5XR. Roush Mustangs are about more than horsepower though; they’re bred for the race track with top-of-the-line suspension upgrades and awesome body kits.

Why Roush decided to haul the car halfway across the country for some testing and showing off in Monterey, California, we don’t know. What we do know is that the two brief video clips that have surfaced on the Internet show a very fast, very loud RS3 Mustang. And by the hammer of Thor that thing sounds sweet. The thing is, we didn’t hear the whine of a supercharger under that hood. We’re not saying that there isn’t forced induction under that hood, but over the earth-shaking sound of that exhaust note, we’re not sure we could (or would want to) hear anything else.