The Catamounts performance group has a talent for giving good spectacle. Boldly envisioned, fluidly executed shows have become their artistic stock and trade. And, whether it’s traipsing “theatergoers” through Flatiron scrub on a summer eve (“Rausch”) or boarding them on an imagined ill-fated DC-10 jet (“Flight 232”) or seating them in a Quaker-meeting-like circle around a morality/mortality play (“Everybody”), the group has been on a tear. Now, with its intimate “attic” set, twisted Victorian costumes and Brothers Grimm set-ups, the Boulder company’s latest, “Shockheaded Peter,” confirms that momentum.