DIY Guide: How to Install a Magnaflow 14815 Exhaust on a BMW E39
DIY Guide: Installing a Magnaflow 14815 Exhaust on Your BMW E39
Stop paying outrageous labor quotes to muffler shops when you can tackle this project right in your own driveway. Installing a Magnaflow 14815 on your E39 drastically improves exhaust flow and gives that classic Bavarian engine the deep, aggressive growl it deserves.
The Short Answer (TL;DR)
This DIY covers the installation of a Magnaflow 14815 Street Series muffler on a 1997-2003 BMW E39 5 Series. The job takes roughly 2 to 3 hours using basic hand tools, an angle grinder, and exhaust clamps or a basic welder. Since you are altering the exhaust flow, pairing this with a performance tune maximizes your power gains.
The DIY Process Overview
Getting this done requires safely lifting the rear of the vehicle, measuring your cut lines on the factory exhaust piping, and removing the incredibly heavy OEM rear silencer. You will need an angle grinder or reciprocating saw to cleanly slice through the factory piping just behind the rear axle. Once the old muffler is dropped, mock up the Magnaflow 14815 to ensure the dual tips sit perfectly flush with the rear bumper cutout.
Depending on your skill level and tools, you can either weld the new muffler directly to the factory mid-pipe or use high-quality stainless steel exhaust band clamps for a secure seal. Make sure to fabricate or adjust the exhaust hangers so the new, lighter Magnaflow unit sits securely without rattling against the underbody heat shields. Double-check your clearances and fire up the engine to check for any exhaust leaks before lowering the car back to the ground.
Why You Should Upgrade While You're In There
When you replace a restrictive factory muffler with a free-flowing unit like the Magnaflow, you fundamentally change the exhaust scavenging dynamics of the engine. Because your exhaust is now pushing out spent gasses more efficiently, your engine is ready to pull in more air. This makes it the absolute perfect time to install a Cold Air Intake and flash a performance tune.
Recommended Upgrade: Performance ECU Tune and Cold Air Intake
A proper ECU tune will optimize your air-to-fuel ratio to take full advantage of your new high-flow exhaust system. This eliminates factory throttle lag, improves throttle response, and wakes up the true horsepower potential of your E39 inline-six or V8.
Frequently Asked Questions
Is welding strictly required for this Magnaflow installation?
While welding provides the strongest and most leak-proof connection, it is not strictly required. You can successfully install this muffler in your driveway using proper stepped exhaust adapters and heavy-duty stainless band clamps, provided you measure your pipe diameters accurately before cutting.
Will the Magnaflow 14815 cause highway drone on my E39?
The 14815 Street Series is engineered to be aggressive under heavy acceleration but relatively tame at cruising speeds. If you keep your factory center resonators in place, cabin drone at highway speeds will be minimal, offering a perfect balance of performance sound and daily drivability.
