Curious - what does part throttle acceleration sound like for the cat back exhaust? Is part-throttle louder than OE, or similarly quiet?
Any time during acceleration you will hear the rumble and roar of the engine, it's not loud and it's designed to minimize drone in the cabin at any steady speed. Especially if your running the factory catalytic converters.
With the windows up you will notice a rumble but you have to listen for it, with the windows down you will hear the exhaust note but it all happens behind the car.
The turndown exhaust is slightly louder by 2-3 db only because the round is bouncing off the ground back up.
The brabus shoots all the sound towards the back of the car so at speed the sound is behind you.
So far i have had 1 person say the brabus tip was too loud, and 2 people say the turn down was too quiet. These were all Cat Back configuration setups.
There has been a total of 50 kits made, 47 in circulation, 33 owners shared feedback on sound. So sound is very subjective...
For me the best way to describe the cat back is that all the sound is outside you won't hear much on the inside. It is louder than stock inside and the more you smash the go pedal there will be more sound compared to stock.
I'm interested but would like to see more pics, either if you have them or assist from users who have purchased and installed.
I'd like to see a head on shot from the rear at car level, not too low, and not up high looking down - for both the OE turndowns and Brabus.
Also, I'm wondering if you can make a cat delete pipe as I don't need them anymore on my 036 - or will that disturb the flow on the catback system you have designed?
Edit: And if you can't make it, what would you suggest that look like (tube diameter, etc.) if I was to have someone locally make it? Yes, I understand that's in the area of IP but I'm willing to talk...
The Cat back section comes with a resonator delete, the front section comes with a Cat Bypass (test pipe).
The factory Front section is one solid part there are no flanges that split the cat at the front Y pipe. So there is no way to simply buy a cat-back and cat delete from me thinking you can recycle the front Y pipe. For this you would need to visit your local Muffler shop so he can hack something together for you.
I can supply you with a Cat Delete pipe but it uses a proprietary flange design which spaces out the 2 pipes at the front leading to the factory style resonator hook up for the cat back section. the local muffler guy will not have access to this style flange and even if i supply the matching flange there is no way to stretch/extend the front Y section to make the new flange work properly with the old OE front Y section.
If you were to use your local muffler shop to make a cat bypass he is limited by the front section which is 68mm pipe (working off memory not 100% sure on exact size) before it splits into 2 where the 02 sensor sits and heads into the factory catalytic converters which are twin 54mm pipes. This is a german car so all the pipes are in metric and the local muffler shop will need to step down to the closes pipe size 2.0" and 2.75"(not a common pipe size in the USA) or he would need to swedge it to the next step up which would not make any sense because the factory pipes will crack due to age and type of SS used at the time.
The only logical thing to do is have a muffler shop remove the factory cats by cutting and welding new pipes and retain the factory style connection where the resonator meets the front section. Do not modify the flange/slip fit connection in the middle you have to retain that. It's designed for thermal expansion by MB.
The muffler shop will need to recycle the old flange on the drivers side right after the catalytic converter, and create a slip fit pipe (passenger side) that will slide in to the factory muffler or my cat back kit.
Flow disruption will be minimal just minimize the amount of welds and internally make sure the welds are flat and smooth (no speed bumps). Pipe size should be close in sizing any time you shrink a pipe you create a bottle neck and unwanted heat entering a smaller pipe cross section. This usually causes a buzzing noise during acceleration because its going from a big pipe down to a small pipe. The velocity will increased as it exists the small cross section and eventually slow down and stall cuasing a deep lumpy sound. Depending on speed this sudden slow down can cause drone during steady cruse speeds. Try to match OE metric pipe size as close as you can with the SAE US standard sizes.
Sound tuning is a nightmare this is where Yamaha excels and they do a lot of the exotic car exhaust/engine tweaking for car manufactures today.