Well, since I don't have HIDs, I honestly cannot answer your question. However that may be, what are you looking for? Just sound? Performance? Or both?
I personally was looking into Conforti's intake. It's just under $360 w/free shipping from M3Motorwerks 
In combination with a chip, Hp gains are noticable at 14Hp and 11lbft. Not to shabby.
Dough
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<span style='color:green'> <u>Proud</u> Member of the BMW Community</span>
<span style='color:black'> 1999 BMW 328i Jet Black --Total Dinan Points: 5 --
<a href='http://dinancars.com/SeriesPrint.asp?prod=335' target='_blank'>----</a> Dinan Stage 1 Suspension<a href='http://dinancars.com/SeriesPrint.asp?prod=335' target='_blank'>----</a></span>
<span style='color:black'> <a href='http://www.ajusa.com/cgi-bin/knfilters/start?r=ajusa&ajr_skey=e2398f2ee8c6388757f9e7fb800 a4cb9' target='_blank'> --</a>K&N Air Filter<a href='http://www.ajusa.com/cgi-bin/knfilters/start?r=ajusa&ajr_skey=e2398f2ee8c6388757f9e7fb800 a4cb9' target='_blank'> --</a></span> | 
Linear Mode
