I just bought a 1996 GMC Yukon 5.7, with just over 100,000 miles on it. It runs/looks awesome except that is seems a little loud. When I am in park, idling, basically not touching the gas pedal, it sounds normal, but when I give it gas (even a little) it's making a bit of noise, kind of like there is a pinhole in the manifold, or possible the lifters. Something like a rhythmic wooshing sound of air, which gets faster and faster the more gas I give it (but not really louder). I will have it looked at, but just wondering if there is something in particular I should be worried about? Or maybe these engines are just a little louder than I expect.

from your discription it sound like the exhust donut gaskets leaking.