Are the two bolts above the intake manifold enough to keep it sealed with less than 10psi boost? Would making secondary clamps that attach to the exhaust studs and press against the bottom of the intake manifold flange be a better idea?

when the two manifolds are mounted the bottom studs should have large thick washers, that way they hold both intake and exhaust. the studs on the under side sit in between a relief in the intake and one on the exhaust, it's a shared stud for both manifolds

and yes, the standard mounting system is plenty for boosted application as proven by many here.

There is no lock washer on these large washers
* 08911-10810 NUT CYLINDER HEAD TO MANIFOLD (9)
* 08915-13810 WASHER-LOCK (5) for upper studs
* 14037-32200 YOKE-MANIFOLD (4) [large washers]

They are a special washer with non-parallel faces.

M8 studs & nuts.

Cool, thanks! I can totally manage this.