UPDATE. Just wanted to add a few thoughts and put a fork in this thread.
1. The hex head bolts supplied in the manifold kit don't allow a socket to fit on cylinders 5 & 6. The indentation in the casting is too tight and you have to use an open end wrench to tighten them down. So, if you plan to torque them to spec (25# ft), it ain't happening on those two bolts.
2. The manifold bolts tend to loosen up with heat cycles. I retorqed them 4-5 times the first two weeks after install. Traditional retainers (oem style where you bend the metal tab) don't work because they don't fit the profile of the Hooker manifolds. Stage 8 won't work because you need 2 -1/4" bolts.
3. My SOLUTION: I bought 2-1/2" cap screws from the hardware store. I cut 1/4" off (otherwise they will bottom out in the head) each bolt. I used 3/8 NORD Locks (ordered thru Grainger). This appears to be the perfect solution. The 3/8" hex bit makes tightening the cap bolts a breeze and they even look more professional. Don't forget to use anti-sieze. The NORD Lock washers are amazing.
4. 3/8" bolts are normally torqued to 25# but the NORD Locks specify 31# for them to function properly. There's a torque chart on their website for the size bolts you're using.