I have also tested head gaskets and bolts...my experience as follows:-

Std head bolts on a multi layer or Coopers rung block do not have the required clamping to stop the gasket blowing under high boost pressures....Std head bolts are good upto t34.63 conversions on grp a gaskets.My T4 @ 34 psi lifted the head and cracked the block around the middle 6 bolt holes,if i'd been using ARP's this would NOT have happened.

ARP's i have used and never had any problems..BUT beware they have to be installed CORRECTLY like COMETIC head gaskets have to be!!!!!!!

Now on WRC middle 6 long stud std out 4..as my block came with this...have full confidence on this as the middle 6 is where the most force is and my head wont lift like it would on std head bolts and crack around bolt holes!IMO its all thats needed as the outer 4 do not want to be as tensioned as the middle 6 (std are stretch,WRC are semi stretch) or block cracking can occur again culminating in premature gasket failure