between the two..
definitely Active Autowerkes.. there's just waaay too many problems i've seen with ESS.. i haven't seen a single car get the claimed numbers.. or anywhere near for that fact..
one of the local 330i bmws here had an ESS supercharger..and well.. it wasn't impressive.. he would still get his ass handed to him an e46 m3.. and would still lose to an e36 m3 with only software, intake, and exhaust....
but if you don't mind me confusing you more..
I would recommend the ASA/Technik kit... i've done plenty of research myself, and when I go F/I.. they will be my choice..
http://www.rennsport.com/forums/forumdisplay.php?s=&forumid=53 to see dynos
EDIT: oh yea. the massive power drop/dip you see on the pre 39.2 ZHP dyno will belike that on all of them.. my cars dyno shows the same massive drop.. it's the ms45 ecu.. supposedely the dis v40 solves/alleviates the issue.. there's a new thread on that dyno too..