The M340i is an impressive car in terms of performance and style but that is not conveyed when viewing its lackluster stock intake system. In stock trim, the M340i comes with a dry and lifeless air box housing a basic panel filter that is also accompanied by an intake resonator whose job it is to eliminate turbo/intake noises. The same noises that those in the performance world relish. Essentially BMW has seen fit to give M340i owners an air box that looks uninspiring, flows adequately but not ideally, and emits no noise. The exact opposite of what the platform exudes otherwise. The Dinan carbon fiber intake for the platform rights these wrongs and delivers a semi-open intake capable of flowing 58% more air than the stock system resulting in additional top end power and increased throttle response. At the same time revealing a more aggressive, sporty carbon fiber appearance, and an increase in sound courtesy of the removal of the intake resonator and implementation of a semi-open design.

In order to achieve the gains in flow that set the Dinan intake system apart, the entire lower box of the system, and not just the lid, has been reworked and enlarged in an effort to make use of as much of the available real estate as possible within the engine bay. In turn, this allows a 40% larger, custom, free flowing filter to be housed within and maximum flow to be realized. However, a secondary inlet has always been desired by Dinan in order to effectively fill the volume of the enlarged air box and increased filter surface area. This desire led to a multitude of experiments being conducted on the effectiveness of a possible open-air inlet in the system. With different shapes, locations, and sizes of openings being tested, the goal was to ensure that the added secondary inlet did not cause any unwarranted side effects such as an increase in air temps in the system. This is commonplace with open-air intake systems where overheated engine bay air is employed in the intake tract. The results of these tests showed that the patterned openings present in the final iteration of the box located on the opposite side from the engine provided a perfect balance of additional volume to assist the factory inlet all the while not causing an increase in turbo inlet temperatures. This was the case regardless of testing conditions (single/multiple gear pulls, constant speed, 0-100mph runs, etc.).

With more air being pulled into the system, throttle response is improved and additional power is realized in the form of max gains of +9 WHP / +8 ft-lbs of torque. The secondary air inlets also allow the intake system to be more audible so the turbo spool and BOV can be appreciated. A stark difference from Dinan's traditional fully sealed systems where induction noise is not nearly as recognizable. Not to be outdone by the increased power and sound, the outwardly visible system is made of immaculate carbon fiber so the under the hood appeal is vastly improved over its drab and utilitarian beginnings. A worthy piece to add to an already impressive vehicle.