Originally Posted by RamTex
08 and older hemi intake manifolds are internal and cannot use a catch can unless you modify them. Now if you swapped to a new 6.1 manifold then you could add a catch can. But im sure there is some mild modifications needed to do that. But at least you would see a performance increase. The only down side is now you would also have to fabricate yourself a new intake tube aswell and in the end would probable have about 600-700$ tied into the swap maybe 500$ if you got everything dirt cheap. Or you could swap to a stock 09+ plastic eagle manifold instead of a 6.1 which might save a few bills.
Cost to date on the 6.1L intake manifold swap is around $1100. That's a manifold, adapter spacers, LMI CF hammer intake, catch can, and hose upgrade. I went a step further and got a set of eagle heads for $600 so I won't need the spacers.
Just drill out the valve cover and add a catch can, saves you a WHOLE lot of money.