All the factory service manuals I've used say 35 Ft..Lbs. on the 3/8 intake bolts, not 40 Ft Lbs.
The 1/4 inch end bolts need to be tight, not twisted off As said some of the after market intake manifold specs. sheets call from 25 to 30 Ft. Lbs.
I do retorque the intake bolts several times after driving it enough until the bolts take a final set and stop moving