ASA and Active Autowerkes(sp?) seem to be the most promising. Rms seems a little shady and ESS probably has the most out there installed. Do a search and you will find more than you could need on this topic
Here's a snippet of an email from Karl Hugh, one of the owners and tuners at ActiveAutowerkes:
"As for the 330i sc with 5 speed manual, we have one that is just being finished up right now. It is making 276 rear wheel HP and 256 ft-lbs of torque in 85-88 degree F weather with 85% humidity after 14 dyno pulls. we have a comparison chart against an E46 M3 coming soon.This car also has the AA exhaust, so you can figure at least 8-10 Hp less on a stock exh. After this 330i is finished , we will be posting the results on our website."
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