Mercedes W204 C300/C350 Dual Open-Filter Intake: What Owners Found

2 min read
Mercedes-Benz W204 C300 V6 engine bay with the engine cover on and the front intake ducts

The W204 C300 and C350 already breathe through a pair of factory airboxes. Owners who swapped to open filters found a deeper growl and years of trouble-free driving. Here is what they learned.

The Short Answer (TL;DR)

On a 2008-2012 Mercedes C300 or C350 (W204, 3.0L or 3.5L V6), a dual-filter intake gives the V6 a noticeable growl under load and a cleaner look under the hood. In this MBWorld thread, one owner ran the setup on his '08 C350 for about five years with no problems. Keep the filters shielded from engine heat and it's an easy, reliable upgrade.

Mercedes-Benz W204 C300 V6 engine bay with the engine cover on and the front intake ducts

What the owner built

The thread starter, on a 2011 C300 4MATIC Sport, built his own version: two cone filters, two 3"x4" tubes, couplers, and two heat shields that mount on the filter clamps. He took the stock paper filters out of the airbox, since you don't need both. The heat shields needed cutting and trimming to clear the tight spots where the filters sit, and he finished the cut edges with edge guard. The thread doesn't give part numbers, clamp sizes, or torque specs.

What changed

  • Sound: about the same at startup and idle, but a noticeable growl under load and at wide open throttle.
  • Power: he said he could feel no loss of power and never put it on a dyno. A C350 owner reported a dyno gain of about 7 hp, though the thread doesn't show the sheet.
  • Reliability: the original builder of the design said he'd run it on his '08 C350 for about five years with no issues.

Diagram comparing the stock W204 V6 grille-fed intake with dual open cone filters

Keep the heat out

One reply made a good point: an open filter sitting in the engine bay can pull warmer air than the factory ducts, which feed from the front of the car. That's why heat shields matter. Keep the filters shielded and away from the exhaust side so they breathe the coolest air available. A kit made for this car takes care of that fit for you.

Going bolt-on instead of DIY

The DIY route meant cutting heat shields and tubing to make everything fit. A kit made for this car bolts on without the fabrication. Confirm your year and engine (3.0L or 3.5L V6, 2008-2012) before you order.

Cold Air Intake for Mercedes-Benz C300 C350 2008-2012 V6

Shop the Cold Air Intake for Mercedes-Benz C300/C350 (2008-2012) 3.0L/3.5L V6

Driving a different Mercedes? Browse Mercedes-Benz performance parts and confirm year and engine.

FAQ

What will I notice after a dual intake on a W204 C300?
Mostly sound: owners describe a growl under load and at wide open throttle. One C350 owner reported about 7 hp on a dyno.

Do I keep the stock paper filters?
The builder removed them and said there's no need to run both once the new filters are on.

Source and real install photos: MBWorld thread "w204 new intakes installed w/photos". Credit to MurderedC300 and GUTTER-BOY.