dual pattern camshaft

Yes and Yes kind of . A lot of it has to do with the combo and mostly your cylinder head selection . Aftermarket heads have a much better intake to exhaust flow ratio so they might need a little less split . The extra lift and duration on the exhaust helps bleed off pressure plus helps pulse the incoming intake charge . This helps create a higher velocity intake charge into the head and intake . It is also helpful in nitrous and bigger cubed motors . If you are wanting a more radical idling motor stick to the single patter cams .