i am using ar catxxx dps and borla exhaust, still had to use some oem parts like enrita said. sounds good, no major drones. I did this to loose some weight on the heaviest car on earth e93, there was no hunting for whp on the first line. it is cheap and sounds acceptable (like a v8 now), did it after full catless on oem pipes and sound improved a lot. Minuses - had to use a piece of oem pipes.
Procede V5, AMS FMIC, AR c-less DPs & Borla exhaust, DCI, CDV, STETT Charge Pipe+BOV, KW CoilOvers, CMGS Meth kit CM10, AR additional oil cooler, Quaife LSD, TD stage 1 turbo upgrade, RIX Gauge, ACT street clutch