Did you degree the cams in?
They're not really necessary. 03/04 Cobra guys have the same TTY-style bolts that 2-valves do, and they regularly push 20+ pounds of boost and 700+ rwhp on stock bolts. Besides, every time you remove the bolts (which you have to trash), you also have to trash the head gaskets. And when I did my rebuild, I found that just a set of gaskets is about $80 if you're resourceful, while the entire FRPP head install kit (which is head gaskets, head bolts, and exhaust manifold gaskets) is only $10 more. So considering exhaust gaskets are around $10 also, the head bolts are actually free, which makes it hard to justify a $300 investment in ARP bolts/studs if you're not making enough power to need them (OP isn't even close).