Custom tunes for the SCT are the best. Here's a link to some free Spartan tunes you can try out with your livewire. Just pick the strategy that matches your truck. I've been using the Spartan tow tune as it gives me the best mileage out of the other custom tunes I have. You'll have a lot of fun, enjoy:
Index of /~amon/tunes
some of the ratings for the Spartan tunes:
Stock+ 20HP - "tweaked" stock calibration
Heavy Tow 40HP - safe to tow Max GVWR of vehicle
Heavy Tow w Engine Brake 40HP - safe to tow Max GVWR of vehicle, with turbocharger exhaust braking
Aggressive Tow 65HP - safe to tow/haul 10,000LBS payload
Aggressive Tow w Engine Brake 65HP - safe to tow/haul 10,000LBS payload, with turbo exhaust braking
General Economy 90HP - daily-use economy file, 7500LBS tow/haul limit
Max Economy - designed for maximum fuel economy; no assigned power or tow ratings
Mild Street Economy 100HP - daily-use performance and economy calibration
Aggressive Street Economy 130HP - daily-use performance and economy calibration
Hybrid Race 150-170HP - (dependant upon calibration) performance calibration
Ultra Competition 175HP - drag-race/sled pull ONLY calibration