The air filter restriction gauge monitors the air traveling through the intake tract. If too much of a vacuum is noticed, it will close up and cut power. Then you must manually reset it by pushing the yellow plunger. This can happen quite often when you're at the track. We've heard of people disconnecting them, but it's up to you.
The Extreme package includes SCT's EGT sensor, which mounts in the driver-side exhaust manifold. If you have already purchased the basic tuner and want to upgrade, SCT can update your Livewire via e-mail and ship you the EGT sensor for an additional price.
SCT notes that you'll need to exercise some self-control if you plan to run the Extreme tune all of the time. Driving the truck hard constantly can quickly fill up the diesel particulate filter, and the truck will switch to the power-reduced Regeneration mode more frequently to clean it. This cleaning mode is something the truck is normally programmed to do, but if you load the filter up with soot, then it will do it more often. If you are a little easy on the loud pedal-which we found difficult to do given the amount of fun you can have at full-tilt-you shouldn't have a problem with the particulate filter.
Just fifteen or so years ago, performance enthusiasts thought fuel injection would be the end of automotive performance, and here we are pushing a couple of buttons and picking up an extra 120 hp. It sure beats bending over the fender all day to bolt on cylinder heads and a camshaft, doesn't it?
The diesel particulate filter is part of the low-emissions mods Ford has been making to the Power Stroke. Basically, it catches much of the soot that comes from the diesel combustion process. The computer incinerates it at a later time. | 
SCT's EGT Sensor kit is part of the Extreme Race upgrade package. It works with the Livewire's warning light to clue you in on rising exhaust gas temperatures. | 
The Extreme Race upgrade is not recommended for long-term use, but if you want to get stupid with an 8,000-pound truck, the extra 120 hp and 230 lb-ft of torque will let you embarrass most sport compacts and even a few late-model Mustangs. |