i think CAB has said for years, 2" headers work way better than 1 3/4 or 1 7/8".
[if and] when i get my charger going again, i have a set of 2" to 2 1/8" step TTI headers i'm going to use on my 446. it has ported RPM's, 11:1 compression, and .590 purple cam, with a 4500 converter.
the car has 3:91's in it now, but i may step up to 4:10's or 4:30's, depending on what size tire i go with.
i'm hoping that combination might make my car a fun ride, even though it weighs a bunch.