I've done both: The Dr. Vanos on my car and the Besian on my wife's car (when she had an E46). I went with the Dr vanos on my car because I just wanted to be able to swap the unit out without the extra work. After doing the Besian kit, it really isn't that much more involved once you have the VANOS unit out but if you don't have good wrenching skills it can be a little intimidating. The directions that come with the Besian kit are very good though.. A quick search on YouTube turned up this video: https://www.youtube.com/watch?v=IBJL9AkS6Qc
Dinan CAI &Throttle body, ESS Tuning TS2, Bimmerbrakes gen3 headers, UUC SSK & DSSR. Achilles oil pump, VAC oil pan baffle
M3 Motor mounts, UUC Trans mounts, Modified clutch style LSD 3.15, TMS front subframe reinforcement, Koni Yellow sports,
H&R sport springs, UUC sway bars, BMW Perf. Rotors, UUC SS brake lines, Hawk HPS pads, CSL replica wheels,
Rotora strut bar, FXR HID conversion, M3 Mirror conversion, BSW stage 1 speakers