All buttoned up, Joe Jill Jr. (left) and Don Spaccarotella set timing to 34 degrees on the Superior DTS dyno. With a pair of 1404 Edelbrock Performer 500-cfm carbs on the intake and exhaling through a set of cast-iron Street Hemi manifolds, it delivered 612.9 hp at 6,100 rpm and 569.7 lb-ft at 5,300 rpm. But we're not done . Replacing the Street Hemi manifolds with TTI 21/8 dyno headers, output jumped to 661 hp at 6,100 rpm and 600 lb-ft at 4,600 rpm. That's a sweet gain of 48 hp and 30 lb-ft. Thanks go to Kenn Funk for the loaned manifolds.