Does an increase in airflow (intake or exhaust runner) move peak torque up or down the RPM band?

I have posted this before; I built a pretty hot 406 sbc, ended up with it in a 92 gmc shortbed. I built the 3" exh. system to dump in front of the axle, it did have a fuel cell, so real headers. I got the bright idea of having tail Pipes bent to go ever the axle and dump behind the rear tires , camaro like, FULL 3" . I COULD NOTICE A DIFF IMEDIATELY WHEN I STARTED IT TO BACK THE TRUCK OUT OF THE MUFFLER SHOP , I DROVE HOME "ABOUT 6 MILES" , AND PULLED THE TAILPIPES OFF, .
I still have them in the shed if anyone wants them , they are just barely starting to get rust spots on them . I paid the guy $100 to bend them up.
Free to a good home ,just pay the shipping.
Will fit any chevy/gmc with headers . shipping from 74021 ---------bob
That sounds good Bob!!