I install these mostly for friends and family members, you can find T-harness for older ford vehicles but I turned up nothing on the LS. The key is, ask questions about the install before they touch your car. See if they like to use T-taps or if they solder the wires. Soldering is always the best, most reliable connection. The bad thing about T-taps is that they actually cut through part of the braid in the factory wiring. The preferred method is to strip back the coating, then using a pick or a small screw driver, spread the strands of the factory wiring, creating a hole in the braid. Then thread the remote starter wiring through the hole, twist it around the factory wire, solder, tape and then I always secure the tape and wires with a small zip-tie just to make it more secure.
DEI makes good stuff, I've installed Autopage and Crimestopper brands as well and never had any problems.
Just find a reputable place to have it done at, remember if the price sounds too good to be true, go somewhere else. Most places are competitive but usually priced about the same.
I install all Two-way remote starter/alarms. The units cost a little more but it's nice having the notification from the remote without having to be in eye-shot of the car. I can usually get the remote starter/alarm unit for anywhere between $100-$150 and then the bypass module between $35-$50.
Also, ask them what kind of bypass module they are using, some shops like to use the key-in-box type of unit. Meaning they take one of your factory programmed keys and put it under the dash. The module reads the chip and transmits it to the ignition. But it causes a safety concern because the factory key is in the car.
The other module is one that needs to be programmed, the installer will need two factory programmed keys to program the module. I would go with this type if I were you.
