The akra is really designed to be paired with the x pipe. Without it the slip on seems to me a bit too deep and smooth. Combined with the raspiness of the x pipe it sounds perfect.
I'm really annoyed to have to spend more than 3k for just mufflers though. Couldn't get myself to buy one even though I have the cash in hand. I have that feeling of being ripped off :/
2013 X5 xDrive50i | Carbon Black | M Sport + M Perf, 333M Wheels
Sold: 2012 E92 M3 | Jet Black, Fox Red/Black | DCT, ZCP