YES, it is worth it. Of course have the intake and exhaust done, but this was my first mod to the car.
I read at http://www.zzperformance.com/zzp/fre...eemod_home.htm
removing the MAF screen on a Series II is good for 10-15% more airflow.
I would have to say, though that I would probably think twice if keeping the airbox as the stock in-box air filters fit good, but they DO allow contaminents around them which makes the oil dirty quicker and could cause problem after a while of building up.
With the custom cold air intakes like ADTR'* and the one I have, as long as you make sure the tb adapter hose, the air sensor connection, and the cone filter all have air-tight connections.