OK, the first thing to know is that your Tahoe basically has two things that make it different from, say, an '88 Corolla or something.
1. You'll see a + sign with a circle around it on the metal shaft of your ignition key. The key has a special chip inside, so that if you just turn the ignition switch with a screwdriver, you still can't steal the car. General Motors calls this feature PASS-Key.
2. The factory alarm system, power door locks, and power tailgate are controlled by the car's computer. You can't just splice wires into the car; you'll want to use a databus module to command the car's computer to arm, disarm, et cetera.
Anyway:
XK01 takes care of #2, but not #1. You'd still have to put your spare key in a universal bypass box, something like the 556U or similar.
It's not that it's the "wrong" module, it's just that it does only half of what you need. Look for yourself:
http://www.bypasskit.com/CompatibilityChart.aspx?prodid=XK01
DLPKGM doesn't even list your car as being compatible. That makes me nervous that these guys at Best Buy might not be well informed. Look for yourself:
http://www.bypasskit.com/CompatibilityChart.aspx?prodid=DLPKGM
If you go to the bypasskit.com website and put in what kind of car you have, they list the CANMAX400 or CANMAX400DEI modules. (The version with the "DEI" suffix docks into that big "door" on your Viper; the non-DEI version gets wired separately.)
However, both of those modules still call for a separate part, a small part that has the same kind of chip you have inside your key.
The PKUMUX and PKUGM2X are also listed as applicable to bypass your transponder key.
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What I would do, I would say here are your options. I'm sure you've already discovered that it's difficult to find someone willing to install equipment purchased elsewhere, or even if they're willing to do it, they'll charge a good bit more. That's how it is, though.
Anyway, here are your options:
1. Find someone who will install what you have (5901 and XK01), and sell you whatever extra part is needed to do the immobilizer bypass. (PKUMUX, or even a universal 556U with an aftermarket "circle-plus" key placed inside. Aftermarket keys are are maybe $15 on eBay, or $30-40 if the install shop is buying them and marking them up.
2. Find someone who will install your 5901 but using his module to do everything, probably the CANMAX400DEI with the corresponding key chip. Sell your XK01 on eBay or something.
3. Get a complete, as-installed price from someone locally using their product, and sell both your 5901 and the XK01 on eBay. It's hard to get Viper product cheap, and you might get more for it online than you would think.