Manifold bolts should not be over- or under-tightened, so use this type of wrench with a foot/pound scale
The distorting, warping or cracking of cylinder heads, intake, 
manifolds, .... On newer engines, head bolts are not torqued to a specific foot-
pound figure... [DOC] [TLE] How To replace Upper intake Plus most engine gaskets in 04 3.4L ... [PAR] Now it is time to remove and install your new lower intake manifold gaskets in 
your ... arm nuts just enough