Hi Leutz, for an Audi 90 front-driver (MKB:NG) a half-system from Kat. Sound-wise the BN-pipes would be my first choice. However, I don’t like the end-tube optics at all. Actually wanted 2 X 76mm tailpieces to remain in a same-body end-tube diameter. Is the wrong car but I wanted the optics like this: http://fox.he-webpack.de/…/product_info.php?… At the BN only a 60mm tube goes out which is then enlarged. Is that the same with the Fox???? Today I telephoned with BN-Pipes.Unfortunately, nothing can be changed at the end tube optics (i.e. diameter). I would have taken a pity otherwise. So I’m really thinking now. Sound or optics………… What do you mean???…. PS: Maybe jmd have a few photos of the Audi 90 that have installed a BN-Pipes or a FOX-system???