Roush's 810-HP Mustang Supercharger Kit Is Now 50-State Legal

Roush Performance's supercharger kit for the S650-generation Mustang GT and Dark Horse has cleared 50-state emissions certification, meaning it can now be sold and installed nationwide without the usual patchwork of state-by-state exceptions that trips up a lot of forced-induction kits this size. Output lands at 810 horsepower and 630 lb-ft of torque, priced at $10,399.

50-state legality is a genuinely meaningful bar for a bolt-on supercharger — California's CARB rules in particular have kept plenty of comparably powerful kits out of reach for buyers in emissions-strict states. Clearing it puts Roush's kit on a very short list of forced-induction upgrades this size that any Mustang GT or Dark Horse owner, in any state, can actually install and register without a workaround.

It also lands the kit almost exactly on top of Ford's own factory-option Whipple supercharger in output — 810 horsepower either way — turning what used to be a straightforward aftermarket-versus-factory decision into a genuine choice between two 50-state-legal paths to the same number.