Originally Posted by BillBoost37
You lost all the torque because you decreased back pressure. Add a back pressure piece back in and you'll probably get torque back.
Trust me.. headers kill low end to a certain degree, which is why we always tell people that changing the exhaust size is bad.
Adding "backpressure" (atleast the automotive term) KILLS power. If his exhaust is too big, adding the correct size shouldn't add backpressure, but increase flow rates.
Headers don't necessarily kill low end power either, but they remove restrictions to top end power, and make the entire powerband smoother. This is of course, if they're properly sized in both primaries and collectors.