An aggressive "shark tooth" grille was offered on the fastback Duster 340 and new-for-1971 Duster Twister models. The Twister was a "performance appearance package" produced in response to increasing premiums on muscle cars, many of which were calculated using the vehicle's power-to-weight ratio as an actuarial gauge. Despite the "dust whirl" side stripes and Twister decals, Rallye road wheels, dual racing mirrors, twin hood scoops, flat-black hood paint with strobe stripes, and plaid cloth-and-vinyl trim interior available in four colors, the biggest engine available was the V8.