I've never heard Kevin (of KWS) say a good thing about the famously thin head gaskets favored by some. I have heard him talk about them, several times.
My take would be to stay away, you will hear loud squawking on these pages when someone has to replace bent '05 valves.
My impression of the wonderous '05 is they have taken the stock motor into the space tuners were using to gain hp. With their motivated engineers they did the job even better than us folks were doing.
Look at the cam timing, rpms, valve size- squeezing hp out of the '05 will be less productive than 1K-4K. They have already done it.