I received the Eisenmann quad exhaust awhile ago, but wasn't able to install it since my car was at the body shop getting a new rear bumper cover. Well, I got my car back so I took the day off so I could install it.
I love it! The design of the right sided tips could be improved upon IMO, but quality is very good to excellent. The appearance of the muffler (minus the shiny stuff) looks OEM. Being the purist that I am, I had a hard time accepting that the right sided tips (which are btw functional) are mainly for looks, but I realized I wouldn't care about what negative things others may have to say. I like the way they look. End of story. The Kerscher quads are nice, but wouldn't go well with the M bumper since they are too low for it. The Hamann quads IMO look funny with the M bumper and are hella expensive. The 335i exhaust could likely be adapted to fit the 330i, but I like my storage trough in the trunk.
Now I have the best of both worlds: a nice and reputable race exhaust and the eye candy to boot.
One more comment. The Eisenmann race exhaust doesn't sound much louder than the stock one on the 330i. The pitch may be slightly different, but the average person would not be able to tell. The GruppeM intake made the car a lot louder. If you want a loud sound, get the SR pipes. Ryan at Eisenhaus had already warned me about this, but I'm cool with the existing system for now, since I (nor the fiance) really care for a car that is too noisy. If I get bored with the sound, I'll get the SR pipes at a later date.
The exhaust system was wrapped, padded, and packaged very well. When it comes to performance items, I didn't think I would care about how "pretty" those parts would look. However, the muffler and components were so shiny, it the eye candy put a big smile on my face.
For those not used to using a cut off saw, I would say have a professional shop do the install. Otherwise, installation is fairly easy and straightforward. Keep in mind that I have the M-Tech rear bumper, so all I had to do was remove the diffuser. If you don't have this, you will have to remove your rear bumper (since it has to be repainted anyway).
I know what you all will say, so this will save you the trouble:
I didn't have my camera with me, but may put together a DIY at a later date. For now, here's a quick summary of how the install went:
1) Carefully unpack the new exhaust. Make sure all parts are in good shape and ready for install. Make note of the exhaust hangers and compare them with those on the OEM muffler/exhaust.
2) Remove rear diffuser on M bumper.
3) I jacked up my car on both sides with a hydraulic floor jack, and lowered it back down on tire ramps, obviously one side at a time.
4) Detach the three exhaust hangers (the ones with the rubber donuts attached) that hold the exhaust system onto the car. Do this by unbolting them--I believe these were 12mm or 14mm bolts or nuts. Once the hangers are off the car, remove the rubber donuts from them. Btw, the donuts don't really look like donuts.
Optional: you may also want to loosen the two front bolts closer to the exhaust manifold that hold the pipes by the cats to the body.
5) The OEM exhaust system will now hang down low enough for you to access the top and bottom of the pipe.
6) This is the hard part. I have an air compressor and a cut-off tool that I used to cut the muffler from the inlet pipe. Cut around the entire circumference of the pipe, immediately adjacent to the muffler on the inlet side. Cut as close to the muffler as you can! If you've never used a tool like this before, be careful not to cut your fingers off. LoL. Always use good eye protection, and a full clear face mask would be helpful.
7) Remove the OEM muffler.
8) Using a die grinder or flapper wheel, smooth out the rough edges of the pipe's (the one on your car) end.
9) Put clamp onto the existing pipe, attach Eisenmann muffler with the OEM hangers you removed from the stock muffler.
10. Tighten clamp. You will have to adjust this later as this helps determine the muffler's position with the ground.
11. Attach the right sided tips and pipe to the Eisenmann muffler. The hanger for this piece utilizes the existing bolt that attaches the metal portion of the rear bumper. I know this must be hard to understand unless you have a photo (which I will provide later).
12. Using the left side exhaust opening of the rear diffuser, make a template of this opening, and cut out a right sided exhaust opening. This should be 100% symmetrical with the left side. Use a dremel cut-off tool, then a die grinder for the finishing touches.
13. You will now loosen the exhaust to muffler clamp, then rotate the muffler so that the tips are all parallel to the ground and situated evenly on the left and right sides.
Addendum:
The right side plastic undercarriage just underneath the battery can be removed completely. I decided to remove it, then cut out a portion just enough to clear the right sided exhaust tips. This way, that plastic piece can still do what it was intended to do: reduce wind resistance and air buffeting under the car.
My diffuser will go to the body shop for repainting.