BMW’s N55 engine was a remarkable achievement, even for a company as adept as building engines and cars as BMW. The first BMW engine to combine turbocharging, direct injection, Valvetronic and Cylinder-bank Comprehensive Manifold (CCM) technologies, the N55 earned “Ward’s 10 Best Engines” accolades in 2011.

BMW N55 3.0L straight-six engine

BMW N55 3.0L straight-six engine

Since its launch in the in the 2010 BMW 535i, the N55 has been stuffed between the front fenders of some 10 different BMW models, ranging from the 135i coupe through the X5 SUV. It’s also proven to be remarkably difficult to tune, leaving owners with few options for added horsepower.

Now BMW performance specialist Dinan has stepped up to the plate with a Stage 2 performance software update, available for owners of 2011-12 335i, 2011-12 135i, 2012 X5 xDrive 35i and 2011-12 X6 xDrive 35i models.

For $1,999, the software nets you 355 horsepower and 401 pound-feet of torque, a gain of 55 horsepower and 101 pound-feet of torque on a 2011 335i. Since the software is uploaded to the car via the diagnostic port, no “black box” add-on is required.

Dinan claims that the software enhances drivability throughout the engine’s range, yet produces noticeably quicker acceleration thanks to the big gain in torque. All BMW-defined engine damage safeguards are retained for your peace of mind.

Excluding the X5 and X6 models (which retain their governed, 155 mph top speed), the software eliminates BMW’s top speed governor, which may or may not be a good thing depending upon your driving habits.

Best of all is that Dinan offers a matching warranty, up to 4 years and 50,000 miles, ensuring that consequential damages aren’t a concern for either the owner or the servicing dealer.

The Stage 2 Performance Software upgrade for the models listed above is available at Dinan dealers now, and a Stage 3 Software is under development. Check out the Dinan website for additional detail, or to find your nearest authorized dealer.