By replacing the OEM downpipes with the ARM Catless Downpipes, you'll be removing the restriction from the OEM converters which will reduce exhaust back-pressure and allow the exhaust from the turbochargers to flow more freely. This increase in exhaust flow allows for the turbos to spool faster, increasing power and torque throughout the RPM range of your 750i.

DYNO PROVEN

Our test car was an N63-equipped 2012 550i GT optioned with the all-wheel drive xDrive system. It came with a Stage 2 tune installed making our baseline numbers 412awhp and 482awtq. After installing the ARM 3" Downpipes and Cold Air Intake, we recorded gains of 48whp and 43wtq over the standard Stage 2 tune for an impressive total of 460awhp and 525awtq. 
 

 

CONSTRUCTION

As with all BMW's, everything is designed to fit in a very compact space, and the N63/N63TU 750i downpipes are no exception. However, BMW did an excellent job of engineering the downpipes to flow in the smoothest path from the turbocharges down to the mid pipe section. Our downpipes essentially followed the same exhaust flow path with a few small modifications to make installation easier. Consequently, the ARM N63/N63TU downpipes mount up to the turbos and midpipes with the same precision as you would expect from the factory 750i downpipes. 
 

 
The ARM N63/N63TU 750i downpipes come with a flex section to relieve stress between the upper and lower portion of the downpipe from engine movement during aggressive driving. To further reduce any tension on the turbochargers, we have developed a lower bracket on the lower portion below the flex joint where it is secured to the transmission housing. These are the same points BMW designed their factory 750i downpipes to be secured, which means a strong and lasting connection safe for all the components on the vehicle.
 

 
The ARM N63/N63TU 750i Downpipes utilize two O2 sensor bungs on each downpipe to allow for reinstalling the O2 sensors in their factory locations. This not only allows for the accommodation of the factory heat shield, but also allows the correct O2 sensor data to be sent to the DME. This is essential for the DME to properly monitor the parameters in the exhaust that are critical to having your 750i motor running smoothly. 

SOUND CLIPS