Pretty safe rule of thumb to follow is to always upgrade your exhaust first, then add to the intake side. Not a end-all-be-all piece of advice, but a good reference point.
Reason being that if you're adding more air in to the engine, it must be expelled. So if you do intake first, you're not giving the extra gasses anywhere to go...therefore not making maximum power from the intake mod.
Get the exhaust upgraded first to deal with the extra gasses you'll be adding with the intake later.
HTH
