Overkill Motorsports is proud to be the premier tuner for the GM 3500 V6. Improving performance and drivability, maintaining a healther transmission and improving fuel economy wherever possible are all high priority for Overkill 3500 tuning. You can be a car enthusiast or consider yourself a regular car owner, you'll appreciate and enjoy the differences in your vehicle every day. We also offer tuning support for our custom intake modifications you'll find below, which combined will get you the most gains for your money.

Features and Benefits:
  • Each Overkill 3500 tune is Made-To-Order based on your vehicle, with no extra charges for customization no matter what
  • Improved horsepower and torque gains throughout the rpm range, gains of 15-20 horsepower on 91 octane
  • Tunes available for 87 octane, 91-93 octane, and with E85 Ethanol if you have a flex fuel vehicle
  • Smooth, consistent, stronger part throttle acceleration
  • Much improved throttle response, more natural feeling to the throttle pedal, no throttle boosters required
  • You'll love an Overkilled transmission! Improved part throttle shift points, reduced bogging, quicker downshifting to your right foot commands. The car will feel lighter on its feet and easier to drive
  • Improved Transmission Life Expectancy - Fixes/improves common issues such as slipping shifts (2-3 shift on Impala especially common), takeoff slip and bump and more
  • Many small features such as speed limiter removal, rev limiter increased, revised cooling fan operation, reduced traction control intervention, and more

87 vs 91+ octane If you're purchasing a tune and looking for the most horsepower, I can do the most for you if you're willing to run 91+ octane, however I realize many Impala owners, for example, wish to continue to run on 87 octane, and the gains are still very noticable and worthwhile, significant time was spent developing the 87 octane tune for this reason. Keep in mind that if you get the Autocal tuning option, you get both, with the ability to switch as you desire.






Overkill tuning is available for your 3.5 through our Autocal handheld. The Autocal handheld allows us to deliver your Overkill tune without you getting your hands dirty and with no relearns required; you to take the Autocal to the vehicle, read the factory file, email that file to Overkill, receive back and upload our Overkill tune. There are no physical installation and no relearns, you can switch between Overkill 87 octane and 91 octane tunes or return to factory tune at any time. Allows easy custom revisions as you add modifications, allows you to drive while scanning (datalog) and send us your scan files to further customize your tunes. You do need to install software on your windows computer to send tunes to the handheld, but no laptop is required.

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Want a great deal? Of course you do! This combo pairs Overkill Tuning through our Autocal handheld with our E85 Flex Fuel kit. You'll get Overkill tuning for 87 and 91/93 octane gasoline, plus tuning for E85 Ethanol fuel which out performs its gasoline counterparts. More information on the Overkill tuning can be found above and more info on our Flex Fuel conversion kit can be found at the bottom of this page, and again, this combines those purchases together and saves you $80!

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Some 3500 vehicles are flex fuel, some aren't, but all can benefit from this retrofit kit which uses a genuine GM flex fuel sensor and installs it into your vehicle's fuel system. For non-flex fuel vehicles, this enables flex fuel capability, which allows you to run E85 ethanol or gasoline or any combination. On currently flex fuel capable cars, it converts the "calculated" system, where the engine computer is guessing the ethanol content of your fuel, to this accurate sensor system.

This setup requires custom tuning. You'll see improved performance over premium octane gasoline by around 8-12 horsepower according to testing, and 20+ compared to 87 octane. Even if you wish to run 87 octane on a typical basis, you can fill up with E85 from time to time to enjoy an immediate performance boost, showing the benefit of Overkill flex fuel tuning.

Kit includes:
  • Genuine GM Flex Fuel Sensor
  • Plug and Play Wiring Harness
  • Black Anodized Top Quality Fittings for Fuel Line Connection
Pontiac G6, Montana and Chevrolet Uplander Owners - This kit, along with Overkill tuning or other custom tuning, will enable flex fuel on your vehicle. Note that this kit will not fit 05-06 3.5 G6s.

Chevrolet Impala/Monte Carlo, Buick Lucerne Owners - Your vehicles often come flex fuel from factory, as noted if you have a yellow gas cap. However, installing this kit will improve performance, by switching from the guesswork calculations from factory to the accurate sensor readings from this kit. Overkill tuning or other customer tuning is still required to activate the sensor input.

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Highly recommended with an Overkill tune! The 3950 tends to run hot and you don't notice it on the gauge cluster. We've seen this lead to inconsistent peformance from vehicle to vehicle, and brings up concerns of oil life and engine life. When getting a tune from us, it's highly recommended that you choose to swap in this 180* thermostat! Typical operating temperatures will be reduced from 205-220*F to 180-195*F. It will allow you to get full performance benefit from your Overkill tune with no side effects for winter use, fuel mileage etc.

Tech Tip: This thermostat is borrowed from another application. It looks different than your OEM thermostat but is a direct fit replacement. Comes with a brand new Oring seal.





Available from Overkill Motorsport is the first and only larger throttle body for the 3500 V6 engines. This 76.5mm throttle body directly replaces the 71mm factory throttle body with the items included in this kit. The larger throttle body size improves airflow at higher rpm, and dramatically improves throttle response. Factory manifold inlet is already sized appropriately to take full advantage without the need for porting. All parts are brand new. Compared to $359 for our competition's factory sized throttle body, Overkill is a much better option!

Works with factory or Overkill tuning with no required changes. However, due to the vastly improved throttle response, if you want the best results, retuning the shift points is beneficial. If you have an Autocal we can provide a new TCM tune easily. If you have an Overkill module tune, we can send out a new Overkill TCM module tune for existing Overkill tune owners at no charge with a refundable deposit on the old TCM module.

Tech Tip: The clamping area of this throttle body is 3 3/8" versus 3" factory. On Impala and Monte Carlo, if you want to keep your existing air filter housing, use tubing part number 15824022 for a direct fit replacement to connect this throttle body to your MAF sensor and air filter box.

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For: Impala, Monte Carlo only!

Once you upgrade to our 76mm throttle body, the small factory MAF sensor is a great item to upgrade with our upgraded options. We offer this kit to do both together and save you some cash! The larger throttle body and MAF work hand in hand to flow more air under hard acceleration and make more power. Larger 3.5" tubing and a large cone air filter make this a complete intake replacement. Great bang for your buck!!

For 2006-09 Impala and 2006-07 Monte Carlo, we sent a complete MAF replacement. It's a larger version of the factory MAF with a 4" inlet and 3.5" outlet. For 2010-11 Impala, we include a larger 3.5" MAF housing made of billet aluminum; your factory card sensor you'll remove from the small factory housing and insert into the larger housing.

Kit will include:
  • 76mm Throttle Body Kit (same kit we sell separately, see for more information above)
  • Larger MAF sensor for 06-09 or 10-11, as specified above
  • 3.5" Silicone intake elbow including breather tube for PCV
  • Cone Air Filter
Tech Tip: Tuning is required for this kit for the larger MAF sensor. Overkill tune users with an Autocal will get an easy tune revision through email. Overkill module tune users can get a retune update, email for details.

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These are Brisk LGS spark plugs, a patented take on surface fire plugs developed by Brisk in partnership with Lamborghini.

A couple advantages:
  • The centre electrode is unobstructed by the ground electrodes
  • The spark event happens deeper in the combustion chamber compared to standard plugs
  • These plugs are made of premium materials, silver core and tipped which conduct electricity better than copper/steel/platinum/iridium used in other plugs
While these may look like another gimmick plug, they provide a noticeable improvement in throttle response and overall engine smoothness and can even provide some increased fuel economy under cruise situations. You'll find these plugs have been dyno proven to add 3-4 wheel horsepower over newer iridium plugs by multiple aftermarket Ford publications. I have personally put over 60k miles on a set of these plugs and unlike platinum/iridium plugs which show wear on the ground electrode leading to a large plug gap and reduced performance, these plugs looked like brand new and held their performance. If you need a tune up, I highly recommend you give these a try, you'll like them!

Price is $7.50 per plug and no shipping charge when purchased separately!