Ah, so that's BMC
Have you noticed an increase in perfomance, if so how much and in what way?
Really tricky to say, I was planning to do some before and after data logging with vagcom but I have lent my cable to a buddy. The filter arrived and I happened to be at APS so had them fit it. It was not essential toget them to fit by the way, its a very straight forward plug n play solution and simply allows more air through than a standard oem filter, also as its still housed in the oem unit you cant see it....
I think if I had been able to log something, all I would have been able to see is that the engine is now working a little more effectively at higher revs, meaning that it should pull a little better all the way to the limiter and should be a little more responsive.... as for bhp gains if its just 3-5 you really wont notice that with your 'arse dyno'
Having the Milltek done at the same time has not helped as the car noise has changed alot with that so its tricky to tell if the BMC had made any difference to engine noise...
When Ian has his done later he might be able to say as he has lived with the Milltek for a while and might be able to notice something if its there...
Sorry cant be any more helpfull or informative.. a good buddy of mine still has a stock S5 so I will see if I can do some instant noise comparisons although there are a couple on youtube..
Before and After Sound Clip