I won to show how is the quad exhaust after i take it off from my car.This foto are with the rieger spoiler for
E60 m- pack bumber.Scratses are from a minor accident.Anyway i just sold this parts for only 150 euro:
(spoiler & 4X80mm inox tips with inox parts and tube to conect left/right side)

maybe you can see the M logo on tips ,is the first letter from the name from a topic exhaust producer: coincidence

 

Nice rear end you got there mang! Are you keeping your stock exhaust that's why you did that custom piping?

 

Yes i have my stock exhaust just cut the tips from there and fit this custom job quads.
But that is from one year ago now is this tips(oval eisenmann):

 

The rear looks very clean and flush!

 

Looks good

 

is there any way, once I get the RPI exhaust that i could have a dummy on the other side for the quad look, but keep RPI performance.

 

I like the round tips better than the oval ones..

I wish all 5ers would come with quad exhausts they look sexier.

 

I'm on the same boat as you. I Pm'd RPI about this setup but never heard from them again. I was asking if they can get me dummy tips on the passenger side that looks exactly like the exhaust tips to achieve the quad look. Let me know if you have any success.

 

The Dinan exhaust system is purposefully designed that way for the E39 M5.

 

looks pretty sick