I ordered the Kelleners tuning kit for my e92 m3 and will receive it next week before new year. They reflash the ecu and delete the first set of cat's "the one after the headers" and replace the second set with 100 cel racing cat's. They claim 40 hp from there kit. I dynoed my car after the 2000 km "1200 m" service and before sending them the ecu to know exactly how much more power i will gain. The test was don on a dynojet dyno and i was runing 98 roz octane fuel "93 ron in the us"