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