Well exactly yeah, it all depends on the way you interval the rpm. Maybe it was over every 1000rpm there is a 5bhp increase, and this goes from 2000 - 7000. I can't honestly remember, but if you find the graphs you will see what I mean. They have worded misleadingly. There was a thread before where this point was brought up.
In the German LE/XE forum this thread is running sometime
Some people say EDS Xe-chip is super, others say it is doing nothing. Seems to be very depending on the ECU type.
But another XE-chip I heard good things about is from RDI (someone did a direct comparison EDS <=> RDI, they have a webservice somewhere => search!). The good thing is that they offer these sometimes for 50 Euro !!! Should be good for about 18 (B)Hp, but if it is only15 then it is still worth the money....