I bought this for the extra noise but as I have a DLV backbox, you can’t actually hear it 
So I fitted it and have driven approx 10 miles with it fitted.
It’s basically new and although I paid more, it is available here for £45.
BMW Z4 2.5i 192BHP 2003 RAMAIR Induction Filter Kit LIFETIME WARRANTY https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F350631270695
It may fit other engine sizes but not sure. Looking for £25 including postage.
So I fitted it and have driven approx 10 miles with it fitted.
It’s basically new and although I paid more, it is available here for £45.
BMW Z4 2.5i 192BHP 2003 RAMAIR Induction Filter Kit LIFETIME WARRANTY https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F350631270695
It may fit other engine sizes but not sure. Looking for £25 including postage.