Egr manifold
everything the other guys have posted is true, What I did with mine was to purchase the Cummins Chromed 49 state intake, as some Cummins parts shops will not sell knowingly sell you non-CARB (California Air resource Board) stuff for a CA vehicle. So, in order to get the part you MAY have to provide them a CPL number from a non-egr truck. When I took my intake manifold off the first time it had a 1/8" thick coating of oily, black soot from the EGR valve all the way to the intake valves, that cant be good for the motor... I used a piece of 1/4" thick brass to block off the hole in the exhaust manifold. I do not get a check engine light as others have reported after defeating egr valve. (I left the vacuum line doohickey and associated wires intact though) I get slightly more boost (could be just the guages marging of error, but boost seems to max out a little higher than before 33-34 PSI)