I have had both bassani and magnaflow. Didn't really notice a difference in sound or performance but even with as well made as the magnaflow was, the bassani is just a little nicer.
I've done Bassani a few times, never a problem. Magnaflow, I've been fighting with their shiat customer service and QC for most of a year. At this point I'll never do business with Magnaflow again.