How hard is to DIY? or is an specific work that should be done by a Dealer /indy shop if your are not a Mechanic?
with proper tools, under 2 hrs.
required: basic hand tools (socket set, extensions, screwdrivers). torx drivers. drain pan. rags. (2) gallons coolant.
optional: air ratchet, compressor, coolant vacuum fill tool.
drain coolant.
remove fan shroud and engine cover.
Disconnect and move aside left and right intake boxes.
Disconnect hoses and electrical plug from throttle body.
Disconnect fuel line that crosses across over the intake manifold. fuel will spill, especially if you have. have a rag handy.
Remove the (12?) bolts holding the intake manifold down. air compressor and air ratchet it nice to have for this.
Lift intake manifold. do not need to remove completely if only replacing the front crossover pipe. use a wire or string to the underside of the hood, to keeping the front of the manifold up.
Remove the crossover pipe. it is top/front of the engine, in the V, under and right of the throttle body location.
reinstall is opposite. you may need (or want) to replace your intake manifold gaskets. I reused mine (140k miles) with no ill effects.
Be sure to lay the hose that runs under the intake manifold in the correct spot.
Refill coolant. i recommend a vacuum fill coolant tool to fill and bleed the coolant system. air compressor required if you use this type of tool.
if you are doing the rear crossover pipe (which i recommend doing at the same time), its a whole other animal. not difficult, but awkward. the LR4's size proportions and location of the pipe make it so you pretty much have to sit on top of the engine to reach it, and yet still remove/install a few screws by feel. its a tight spot and you will get some scratches on your hands.