A little later than anticipated, I am back with my next update.
I have always enjoyed the fact that the Z4 has a slight edge to it. I love the engine - the 2.5 is a peach. However sporty the exhaust note lacks an edge, well, for my taste. I like the sports car sound, it contributes to a more visceral experience. So, I want a sportier exhaust.
My prerequisites, more noise, obviously. Paradoxically, something quiet. At least, enough to use on motorways (spend altogether too much time on motorways) and have a trip to Europe this summer.
For the exhaust I had two options, a custom job, something like CJ has done and MrWhippy is planning, but I lack their skills. Option 2, a direct fit factory box. I did a lot of research, and looking through the forum I kept seeing one theme regarding exhausts… "manufacturers A, B and C are good. There's Eisenmann too, great but too expensive." I quickly wanted Eisenmann. Then I bought the Performance BMW magazine for the Z4M CSL article, there was a small piece in the front about A-L Tuning offering 20% of Eisenmann and labour. Hurrah
I then had a look at the Eisenmann web site, they offer an array of back boxes for Z4s, I was interested in two. A direct replacement twin box or a two box (standard and t-pipe) quad system. There are three sound levels; Standard (OEM equivalent), Sport and Race. I contacted Eisenmann directly and was told that the Sport is similar to OEM but becomes progressively louder than the OEM up the rev range. Race, is just loud. The guy in Germany told me to forget it if I ever wanted to use the car for a long motorway journey. For the twin box setup the second pipe adds a little to the sound, but nothing dramatically different from the single box. It is primarily a cosmetic addition. At no time did anyone mention or were there any discussion about performance gains :wink:
I spoke to Mike at A-L Tuning (he worked on the Z4M CSL in PBMW - good guy and very patient with all my questions), he without being led he said the same about the sound levels. After some discussion I ordered the quad Sport box. Eisenmann hand build to order so there is typically a 3-4 week delivery time. In early February I handed over a cheque and went home to wait.