Having owned 4 Grand Prix GTPs and professionally tuning 3800s since 2003, it's with great pride that Overkill is a premier 3800 tuning service. Improving performance and drivability, improving engine safety with increased boost pressures, maintaining a healther transmission and improving fuel economy wherever possible are all high priority for Overkill 3800 Supercharged tuning. Its with confidence that an Overkill PCM offers the best quality 3800 tuning, the most features and benefits.

Features and Benefits:
  • Each Overkill 3800 tune is Made-To-Order based on your vehicle, with no extra charges for customization no matter what
  • Improved Engine Safety - Extensively revised fuel targets, knock sensor enablers, abuse mode settings, and more create a safer tune for stock and smaller supercharger pulleys
  • Improved Performance - Smoother quicker acceleration, sharp throttle response, reduced KR, typical gains of 10+ wheel horsepower with normal bolt-on mods
  • Improved Transmission Performance and Life Expectancy - Includes skip shift enabling, quicker shifting, lowers fluid temperatures
  • Removes P0128 code for 160/180* thermostats, P0420 code for high flow cat converter, codes for EGR, EVAP and rear O2 sensor upon request
  • Many small features such as speed limiter removal, A/C compressor shut off under heavy throttle to regain horsepower, revised cooling fans with key off fan on enable, reduced traction control intervention and more
  • Tuning available for aftermarket camshafts, aftermarket MAF sensors (Overkill ASI for 04+, LQ4 85mm, LS7 4", LT1 metal), aftermarket injectors (42#, 60#), gear ratio swaps to 3.29 and 3.69 from stock 2.93
What makes Overkill tuning better than the rest? Attention to detail, amount of features, continuous improvement. We do what many others can't and don't, here are some examples:
  • Transmission Shifting - You'll love how the transmission behaviour is fully recalibrated in an Overkill tune and improves how the vehicle drives
  • Torque Management - While others zero out a common lookup table or disable a master switch to fully remove, we reprogram torque management to remove power limiters but still allow engine depowering during transmission upshifts, critical to transmission life expectancy
  • 2006+ Tuning - We were the first to offer 2006-2007 Grand Prix tuning, still the only ones to offer 2007 tuning where the fuel gauge doesn't work in reverse, and still the only ones to offer a core exchange and deposit refund on 06-07 modules
  • Maxing Out MAF Sensors - Common 04+ GP problem, appropriate revisions for protecting the motor if you go beyond 11,500 htz
  • Boost control for MPG - We're the only ones that use the boost bypass valve to limit boost production at cruising, which improves MPG
  • Idle Surging - Overkill tunes offer a more stable idle with aftermarket camshafts and corrects the dash light dimming issue
  • Correct Gear Ratio Programming - More correctly programs aftermarket gear ratios versus the HP Tuners method
  • Corrects and removes hard start issue on 04+ Grand Prix created when installing 60# fuel injectors
  • Corrects common observed fuel trim issues which vary year to year including high negative 04+ Grand Prix trims
Simply input your vehicle mods in and we'll take care of the rest. If you have a complex build, feel free to email to discuss instead at willoverkill@gmail.com






HP Tuners Suite: A great way to provide our Overkill tuning is to sell you your own HP Tuners suite. If you feel you'll need more of a personal touch than a flash tune, but aren't sure about getting a local tune, this a great solution to let us handle your tuning needs through email, with the ability to tinker yourself as you desire.

You'll need a laptop to read, scan and flash from inside your vehicle. You can then provide us with your factory file, we provide Overkill tuning, you provide scans and we provide revisions as needed. The purchase here includes no charge revisions for as long as you own your 3800.

Standard vs Pro The tuning suite itself is the same, the difference is the Pro allows for external inputs, such as a wideband input which we will offer in the form of a rental. Wideband tailpipe readings will help us dial in the full throttle air/fuel ratio, especially important on supercharged setups, if you don't already have a wideband gauge set up on your vehicle.



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More hood clearance is often required when installing a fullsize intercooler on a Series 3 04-07 Grand Prix. Our solution is this adapter plate which rotates the throttle body, gaining 3/4" of hood clearance. Includes a gasket to go between the plate and supercharger, no silicone required, plus stainless fasteners for both the plate and throttle body for a nice look.