Well for a CPU that costs more than 1000 EUR or more than 1200 USD if I'd have to translate the same value.. I would of at least expected it to go beyond the 5.5Ghz mark, if the word badass comes to mention, which it doesn't to me
It's a nice OC if on air compared to it's stock speed, but still for it's price class, it's certainly not worth buying imo. Cheaper CPU's seem to OC much higher speeds than these over priced X series CPU's.
If I were you, I'd try sell it and get the cheaper 3930K or 3820 and do the same speed, which is more fun to me and it gives the end result a much higher value

And this way you'd only save more money too and get more fun out of your OC