We are pleased to be a premier tuner for the 2012+ GM 3.6 Direct Injection V6, codename "LFX", found in your 2014 and newer Impala, 2013+ Cadillac XTS and 2012+ Buick LaCrosse.

We've long been GM V6 tuning specialists, tuning sedans like these that people have bought for practical purposes but want that extra performance. If you want your 300 V6 to feel like 300 horsepower and beyond, that's what Overkill tuning can do for you. Overkill LFX tuning is a performance recalibration of the engine and transmission computers. The benefits of an Overkill tune are straight forward: More power, more instantaneous, improved transmission performance, and proper support for your additional modifications. Whether you're an enthusiast or consider yourself a regular car owner, these are changes that you'll appreciate and enjoy every time you drive your Impala, XTS or LaCrosse.

  • Horsepower and torque gains of 15-30 on 91 octane and 10-15 on 87 octane anticipated
  • Stronger mid-range power, less peaky feeling to the power delivery
  • Improved throttle response, more natural and consistent throttle feel
  • Increased fuel mileage capability, will depend on your driving style
  • Overkilled transmission revises the part throttle shift pattern will downshift with less throttle input, upshift at better engine rpms, reduce torque converter bogging around town, and improve how the vehicle feels in daily driving by feeling lighter and easier to drive
  • Support for your other aftermarket modifications including our intake system, aftermarket exhaust systems, our 80mm throttle body, JacFab intake spacer and more.
  • Speed Limiter Removal, Engine park rev limiter raised
  • No charge revisions for your future modifications, including no charge for our throttle body upgrades

What you'll get with your purchase:
  • An Autocal handheld tuning device, with software on a USB drive
  • Overkill 91/93 octane tune
  • Overkill 87 octane tune
  • Overkill E85 Flex Fuel performance tuning in each tune (if you have an E85 Flex Fuel ready vehicle)
  • Tuning support for datalogging and custom revisions
  • Tuning support for new mods as you add them, for as long as you own the vehicle

Why get an Overkill tune versus the competition?
  • Specialized in the LFX motor. From revised cam phasing, fully reconstructing spark timing tables and fully revised throttle calibration, an Overkill tune is more comprehensive than what you'll get at your local dyno shop. Our tuning includes comprehensive peformance calibrations on both regular and premium gasoline, and on E85 Ethanol; our competitors commonly don't offer 87 octane or E85 performance tuning.
  • Datalogging. You'll get your Overkill tunes but it doesn't stop there. You can scan with our handheld while driving and send that data for review and tune updates, to get a tune that's more customized for your vehicle. Our main competitor offers this service for significant extra fees
  • Support for your mods. Not only are we the only company with an E85 Flex Fuel conversion kit or a larger 80mm throttle body kit, but we also have the right tuning to ensure you get the most from them! Our main competitor offers a preset tune meant for 100% factory unmodified vehicles only
  • Retunes. With our handheld, retuning for your future modifications is complimentary and easy to provide

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EFI Live Autocal is an easy way for us to deliver your Overkill tune. The Autocal handheld is a handheld you take to the vehicle to read and write the tunes, no laptop required. Our tunes are supplied through email after a quick exchange where you read your vehicle, email us the factory tune file, and receive back your Overkill tunes. The handheld fits in your glovebox or center console to easily switch between different Overkill tunes or return to factory calibration with a few simple clicks and a few minutes. Datalogging (scanning your vehicle and sending the saved file) allows us to dial in your custom tune at no additional charge. Receive updates for new modifications at no charge.

The only larger throttle body for the 2012+ LFX 3.6 is available here at Overkill. The factory throttle body is 72mm, as are ported units on the market. Our 80mm throttle body solution dwarfs the stock unit and will allow the your engine to breathe, because your factory intake manifold has an inlet of 80mm already! The improved airflow will result in dyno tested gains of 9 wheel horsepower, improved throttle response (particularly with Overkill tuning) and changes the intake note of the V6 to a deeper growl at heavy throttle.

Note: Won't fit the factory intake. You'll need to build yourself a 3.5" intake system to use with this system.

After several years, I've decided to stop building intake systems for the 14+ Impala, however here's the info you need to build your own:
  • MRP Manufacturing 3.5" GM Slot MAF Housing with honeycomb screen (Available On Ebay)
  • Silicone Intakes 3.5" 60 degree silicone elbow
  • 2x Gear Clamps with a 4" or 102mm maximum outer diameter
  • 1/2" hose barb connection and 24" length of PCV/Fuel Hose available at NAPA
  • Air Filter with 3.5" outlet
If using our 80mm throttle body, you're all set. If using the factory throttle body, you'll need a 3.0 to 3.5" reducing ring; if you get Spectre 9731 that we used it will include the reducing rings.

Drill and install the barb into the silicone elbow, run the 2 feet of 1/2" hose to the valve cover fitting, swap over your MAF sensor, finish up your installation.