Get a take off stock unit and have it OEM modded. It sounds to me like you would likely want to use the long pipe replacement rather than both or the straight through method. Put it on your car and sell the magnaflow part. Depending on how parsimonious you want to get with shopping the take off and patient selling the magna you can get out near zero spend and have an exhaust that does not drone and isn't as anemic as stock.
2012 E92 Space Grey with fox red/black/black, comp, premium, DCT, premium sound, sirius, heated seats.