The N55 has a great voice. The factory exhaust just keeps it quiet. You hear more intake whoosh than straight-six, and the valve does its best to make sure the neighbors never know what you drive.

The Dinan Free Flow Axle-Back Exhaust for the BMW F30 335i and F32 435i lets it sing. It cuts back pressure for a Dinan-tested gain of 6 HP and 5 lb-ft at 6,600 RPM, and it runs a Helmholtz chamber to take the drone out of highway cruising. This version finishes with twin 3.5-inch ceramic black, laser-engraved tips.

How the Dinan Free Flow Axle-Back Exhaust Handles Drone

Most louder exhausts are fine at full throttle and tiring at 70 mph. Dinan tuned this one with a Helmholtz chamber that targets low-RPM resonance, so the sound goes from civilized around town to properly aggressive when you lean on it, without a constant hum in the cabin on a long drive.

The whole system is 16 gauge T304 stainless steel and mounts on the factory brackets and hangers, so it fits like an OEM part. One thing to know: the factory computer-controlled exhaust valve is eliminated, so the system does not switch between quiet and loud modes the way stock does. Dinan part number D660-0045-BLK. Sold by AutoTecknic, an authorized Dinan dealer.

Is the Dinan Axle-Back Exhaust Street Legal?

Yes. It sits behind the catalytic converters and does not affect emissions. Dinan lists it as legal for sale or use on emissions-controlled vehicles. Local noise rules still apply, as with any aftermarket exhaust.

What's Included

  • Dinan T304 stainless steel axle-back exhaust with twin 3.5-inch ceramic black tips
  • Clamps
  • Hangers

Key Features

  • Dinan-tested +6 HP and +5 lb-ft at 6,600 RPM
  • Helmholtz chamber reduces low-RPM drone
  • 100% 16 gauge T304 stainless steel
  • Twin 3.5-inch ceramic black, laser-engraved tips
  • Uses factory brackets and hangers for OEM-style fit
  • Factory exhaust valve eliminated
  • About 1.3 hours to install

Vehicle Fitment

Fits the following N55-powered BMW models:

  • BMW 3 Series / F30 Sedan (2012-2015): 335i
  • BMW 4 Series / F32 Coupe (2014-2016): 435i

Installation Notes

This is a bolt-on axle-back. With the car on a lift, a shop will have it on in about 1.3 hours. At home on jack stands, give yourself an afternoon and a helper to hold the mufflers.

  1. Safely raise and support the car and let the exhaust cool completely.
  2. Handle the factory exhaust valve exactly as the Dinan instructions direct, since this system eliminates it.
  3. Loosen the clamp ahead of the rear mufflers and remove the factory axle-back section from its hangers.
  4. Fit the Dinan axle-back on the factory brackets and hangers, and align the tips in the bumper cutouts.
  5. Tighten all clamps, start the car and check for leaks and rattles.