2010 Roush 427R Ford Mustang First Test

Twist the key and the exhaust erupts with a ferocious bellow. In enclosed garages, it is a fearsome explosion that sets off car alarms and nasty looks. Out in the open, its thunderous note turns heads and raises eyebrows.

"This can't be legal" is your first thought.

The idle is too lumpy, too raspy, too loud. It's a dull rumble that becomes a guttural roar -- at quarter throttle. Declutch a cold engine and coast to a stop, and the exhaust crackles and sizzles -- the sound of raw fuel hitting hot metal.

"I'm going to jail" is the next thought, but this one comes with an evil grin.

There is something unapologetically ballsy about Roush's latest creation, the 2010 Roush 427R Mustang. Even though this latest version makes more power, the model's three digits come from the 427 horsepower put out by the first series of 427Rs sold in 2007. As for the R, take your pick: Roush, racing, righteous, run for the hills. We say it stands for rudeboy.

Forget ever flooring a 427R within city limits. With 435 supercharged horsepower and 400 pound-feet of torque underfoot from the Roots blown 4.6-liter V-8, you're guaranteed instant burnouts and such a racket that, by the time you've made it to second gear, the local constabulary will be lighting you up and politely asking to see your hands.

This is not idle exaggeration. I spent three days with the 427R among the urban canyons of Los Angeles and found few places where I could safely lay down the loud pedal without drawing attention from the boys in blue. I had one cop flash me his high beams as I coasted past -- foot off the throttle. I swore another flipped a U-turn for a closer look. Any wonder why? Just look at that paint job. Ford's torch red combined with Roush's reverse Starsky and Hutch decals draws more cops than Dunkin's free-doughnut Friday.