Curiosity about modified Tahoe

[BlackHawk]

Yesterday I saw two Chevrolet Tahoe, they made a huge acceleration that is not normal for a Tahoe. When they accelerated they made a very loud sound, not the sound of a V8, but a sound like a jet (like the Porsche Turbo for example). What modification have those Tahoe? (Is a procharger??)

 

[07burb]

Kinda hard to tell without any pics of engine bays or a link to more specific information. I'm going to assume probably just an exhaust system on them.