UPDATE: 10-02-15 - Dual exhaust conversion
I finally got around to installing the 335/435 exhaust to my 428i. Based on glowing reviews, I drove the 1.5hrs from my house to Mike's Mufflers in El Monte. Let me say first that I HIGHLY recommend this shop for anyone looking for any kind of exhaust work. They are very professional and conscientious. The technician who worked on my car, took his time, answered all my questions, and was clearly very interested in doing a good job and making sure I was happy. Overall I am very very happy with this mod. I think the dual exhaust looks fantastic, especially with the Cyba tips.
Installation:
As others have mentioned this is not a straight swap as some custom work needed to be done. Any decent muffler shop can do it though. The first thing I noticed is that the 428i muffler is much larger than the 335/435 muffler which didnt present a problem. I was just surprised to see how much bigger the 428i muffler was. The muffler pipe also does not line up with the the existing pipe on the car. It is too far towards the center of the car compared to the existing pipe. The technician had to cut off the pipe at the muffler and fabricated a new one made of two pieces welded together. This new piece was then mated to my car using the OEM muffler clamp.
Another custom task was the need to move the existing exhaust tip locating pins back and cut the outlet pipe in front of the locating pin. I did this because I am using Cyba's 3.5" clamp on exhaust tip which sticks out a bit more and shows more of the outlet pipe.
The final custom task was a new exhaust hanger piece on the right side. The original hangar was to short and did not fit all the way into the rubber hangar support so the technician made a longer one that fit completely through the support piece. I dont think this piece was really necessary but it showed how careful Mike's Muffler is.
The sound:
I did this mod purely for looks so I was not so worried about the sound. However, there is indeed a difference in sound so I thought I would comment here. There is definitely a throatier sound than compared to the stock 428i exhaust. I can hear more of the exhaust in the cabin as well. Overall, I just hear more of the exhaust all time which but the sound is nowhere near loud as one would expect from the stock muffler. There is slight drone between 40-60mph and 1500-2000 rpm in ECON mode. Again this drone is very slight and nothing that would annoy me. In Sport mode there is no drone as the rpms do not dip below 2000.
Here are some pics:
My car at Mike's Muffler:
The locating pin moved back 1" after cutting off the excess pipe:
How the Cyba tip fit before and after moving the locating pin back 1" and cutting off the extra length of pipe:
The custom pipe mated to my car:
The custom exhaust hangar:
The end result. I noticed the right exhaust tip is lower than the left by 1/8", otherwise the alignment is perfect. I am going to let it settle a bit and then adjust it.
