Aftermarket air filter - two thumbs down...
I've been running an aftermarket air filter since last November.
It was bolted straight onto the MAF sensor. Looked good, sounded good, but probably lost me about -15bhp because of the hot air I was sucking in.
Last week when the sun came out - 16-degrees, my engine felt sluggish and tired, so I took the aftermarket filter off and re-fitted the original Alfa system.
Straight away, my erratic idle levelled out (back to 500-1500rpm) - with the Wolfrace filter it was almost stalling on idle, and power is definitely up.
Also, as I haven't reconected the pipe from the filter housing to the inner wing pipe, I've got the induction 'roar' that I wanted with the aftermarket filter.
So, if you want a bit of induction roar, simply pull apart the filter housing from the inner wing pipe.