It should be very inexpensive to have the cats replaced with a straight pipe. You can get the pipe for 30 bucks or less. I can't imagine you guys don't have a welder in the shop and somebody that can weld decent. Should only take them 30-45 minutes to cut the cats out and weld in the new piping.
2008 135i - Cobb AP, MS DP's, Berk street exhaust, AMS IC, BMS DCI, CDV delete, Quaife LSD, M3 control arms, M3 rear SF bushings, SS brake lines.