Had the headers on my 550i for a while and they worked great.

$2000

Here is a dyno showing the difference between stock versus these headers:

 

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do they set off cel? does it make a difference in sound with the quad exaust? I have the same exact setup as you

 

If you install catalytics with these headers (you should install high flow cats), you shouldn't see a CEL. I got a CEL because I ran the car without cats but then had the ECU re-flashed to ignore the downstream o2 sensors. Pretty typical. You can optionally install downstream o2 simulators or try the ol o2 extenders.

This is by far my favorite mod on the car. Unbelievable how few people actually do this mod. It also makes the car sound very aggressive and clean, as if you can hear each cylinder firing. Pretty awesome.

 

Also, look at the torque gains around 2800 RPM...an additional 65+ lb/ft or torque that you can really feel!

 

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Are these still for sale?

 

do they fit a 545i?

 

Yes.

Yes.