This is not correct.
I havent installed Dinan or Eisenmman exhausts but all the Supersprint and Remus I have installed on X5s and other cars are straight bolt on jobs,as they should be since they have been designed specifically for that car and the cost is therefore higher than if one was to buy some of their Universal mufflers which are obviously cheaper but then you would have to cut and weld and pay for the extra labour of fitting!
It is acceptable to have to cut-off your oem mufflers ,if in my case your want to install the oem 4.8 mufflers on to a 3.0 Diesel!