I feel like it is possible to get a similar sound with the 1M since the engine is the same. There just seems to be a difference in back pressure with the OEM 1M exhaust and even some aftermarket systems that causes that low burble, off throttle. On throttle sounds good, but as soon as you let off on the gas you get that 'slapping' burble.
Personally I prefer the sound of this 335i system by SuperSprint.
or the RD