Mopar Action Tech Questions – Exhaust

Tech Question

Paul Mc Gough, Bakersfield, CA, 1973 Plymouth Duster 318

Hey Rich,
I got a question on exhaust. Right now I have a stock ’73 318 duster and have a set of hooker headers (5901 HKR) and 2-1/2″pipes with Flow Masters. I’m building a 360 with 340 J heads. My issue is the headers on the driver side hang down low and has already flatened two tubes.I have been thinking of going with the hedman short headers (hed-78500) andan X pipe to replace the speed bump finders. Do you think I will lose a lot of power with this set up? Thanks, Paul Mc.


It depends! If the engine will basically stock, not a cammed-up, single-plane high-rev deal, then the loss, if any, will be small. However, once the HP gets north of 400 or so, the engine — if you look at the dynocurve — will begin to “nose over” (lose HP) too early in the RPM range, so you’d be killing HP and not even picking up any mid-range.


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