Hi, Nelson,
I had mine done coz due to my rear mufflers & Cat with some small hole.....visible.....and also start to make noisy sound......
So i changed to a UNiversal Rear mufflers, center muffler to replace the cat, with sensor fixed!! A new tip at the rear + Labour charge.......all under RM800......Haahaha......But everything was done properly......as the rear muffler is black in colour, so from the back it looks original, just the tip.....looks like AC but its not......hahaha........sound ?? Just like what we like.....BMW sound!! But now the engine runs better, smoother & better pick up.......i guess becoz the CAT is out.......the exhaust Flows Freely now.......hope this helps......as i do not want to burn a hole in my wallet too........as long as it maintains the BMW sound.....and better power.......im happy!! Im quite sure the mileage is better now......clocking now!! Hehe.......Cheers......mine is also a BMW 520i 1996 24V I-6.....