I too have a '07 3LT Tahoe.
You haven't indicated if you want a full exhaust system, a cat back exhaust system or an axle back exhaust system.
Not sure where you reside, but if you replace the entire exhaust system with headers, hi flow cats, free flow muffler and remove the resonator, you may encounter smog certification issues when it comes time to smog your Tahoe.
If your considering a partial replacement from the catalytic back, I wouldn't spend the money on one of those packages, as they are quite expensive. I would just take it to a reputable exhaust shop, have the muffler and resonator removed and replaced. This is what I did.
If you're one of the handful of vehicle owners who don't care about passing smog, then I would imagine you would elect to do a complete replacement.
When I had my 2010 SS Camaro, I read that "tuning" the computer, leaves a modification imprint on the computer. What that means is that a mechanic with the proper equipment will be able to identify that the vehicle was modified with a "tune." Again, if you're one of those folks who don't care about that, there are several "tuning" chips out there that will accomplish what you want.
