I had a 97 1500 4x4 with a 5.2 and  5 spd tranny. I put a Gibson single cat
back exhaust and a K&N filter kit on it at the same time. I noticed an
improvement in top end power, was much easier to pass without downshifting.
Mileage went up a bit too, I was averaging around 21mpg, 22 or a little
better if i was easy on the gas pedal. The Gibson exhaust had a nice deep
mellow tone, wasn't at all obnoxious. I think i paid around $300 - 350 for
it, long time ago, not sure. The K&N filter was pretty cool, it was just the
regular 14" chrome type, just a bottom and a nice lid with a round filter,
looked great, bolted right onto the the plenum. My recommendation, if your
gonna get the air out faster, do something to get more in as well.

Simple answer. Stock truck, no.

Gibson, Magnaflow. Or if you really want sound that will chase you out of
the truck flowmaster muffler's.

Roy