About 4 weeks ago I had a full system custom stainless steel exhaust & de Cat from a recommended company fitted.
My car is a 530d Sport E60 2004 Auto. (42k)....
It was a Mid Sport tune I opted for instead of the full on Race sound. So you could only really here the exhaust when you put your foot down.
First couple of weeks the exhaust was fine, but then travelling home from work one time it went very loud, again only when I touched the accelator. The thing is its happening quite a lot now but its not a continual sound it comes on and goes off again at irregular periods, but the sound difference is very alarming when it kicks in, the car vibrates.
There is no loss of power!! could it be the carbon build up in the car???
Just really want to know if it's normal, as I took the car back to where the exhaust was fitted but it wasn't making the louder sound when it was there, and the guys didn't know what could be making the noise. They just said to monitor it, not very helpful.
Thanks for your help