Originally Posted by RDSport
I will not speculate. Let us test them and tune our EMS to them, and then I will post. As you can see, the secondary downpipes are where the OE cats are, so the system is a little more involved than just slapping on headers and driving off. We are testing a standard 4-1 merge collector, but given the quality of the OE header we do not expect to see much improvement with this configuration. The Tri-Y is expected to give a fatter torque curve, but the install may become a little costly as a metal cat will be required.
I figured you wouldn't see much gains with new headers as the stocks are already pretty efficient being they don't have cats welded into them like the 46.