I used a Magnaflow 12138 that didnt come with tips. I dont know why everyone insists on the 14815. Magnaflow makes a bunch of universal mufflers in different sizes, such as ones with a 2.5" or 3" inlet.
The only good thing I guess is the 14815 comes with tips. But, IMO it's a better option to go with one without tips. Then you can have the muffler shop mount it at 45 degrees instead of having a 90 degree bend in the exhaust piping, and you can pick whatever tips you want.
As far as drone, there is no drone on mine on the highway. I still have the stock cats and resonator in. Haven't noticed a change in power in either way, but I did it mainly for looks and sound.
AW/Terra | ZSP | ZPP | ZCW | iDrive | CA
Mods: BC BR coilovers | Blacklines | M-tech rear | dual exhaust | M3 steering wheel | BMW SSK | ZHP shift knob | High-kick CF spoiler | NBT Retrofit
M3 front control arms | M3 rear guide rods | Manzo rear toe and camber links | Monroe rear shock mounts | Varrstoen ES1 19x9.5+20 Front, 19x11+25 rear