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

But now BMW performance specialist Dinan has stepped up with a Stage 2 performance software update that is available for the 2011-12 335i, 2011-12 135i, 2012 X5 xDrive 35i and 2011-12 X6 xDrive 35i models. For a price of $1, 999, the software offers 355 horsepower and 401 pound-feet of torque and a gain of 55 horsepower and 101 pound-feet of torque on a 2011 335i. The software is uploaded to the car via the diagnostic port and so no “black box” add-on is required.

Dinan claims that the software enhances driveability throughout the engine’s range, yet produces quicker acceleration due to the significant gain in torque.

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

Source: Motor Authority