J-Pipe for drone reduction

I have long been a fan of my muffler/secondary cat delete on my 330i, but as of recently it was too much to bear drone wise, which forced me to go back to stock. Granted I am looking to get a new BMW this year, I would still like to put an exhaust on it that can be custom, won't cost an arm and a leg, and is close to drone free.



SOLUTION: I have been browsing the web far and wide and come across J-pipes, also known as a Helmholtz resonator (example below)







The piping is anywhere from 28 to 48 inches long depending on where your peak drone is coming from on your RPM band. The pipe is capped on one side, and the other is typically welded after your last muffler and before your exhaust tips. The piping captures vibrations from the exhaust, funnels it through the J-pipe, then comes out significantly less if at all. The muscle car community and 370Z are crawling with information about it as well, all with great feedback from the J-pipe.



My question is, why hasn't anyone done this on BMW's yet? I haven't found any examples of it on a I6 engine configuration, which makes me wonder if it's only applicable to V6/V8's. Has anyone heard of these/have some feedback?



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