Ithink those are like add-on ecu's, or a new program for the ecu. Usually they get rid of rev limiters, change the fuel maps ... same stuff that a Shark Injector (your car is OBDII ?) would do. Not so sure about 20 HP though. You may be better off with the cam shaft ...
<span style='color:green'>Nobody likes you.</span><img src='http://www.bmw-forums.com/forum/html/emoticons/ph34r.gif' border='0' alt='user posted image' />
<span style='color:green'>Are you experienced, little girl? I want to know what goes on in your little girl world.</span>
<span style='color:green'>I'm the man! I'm bad, I'm so bad I should be in detention. I'm the man!!!</span>