Hi there...
U might want to try Superchip, they should have the chip for your car..
Else it's actually more worthwhile to try out the UNICHIP since ur car does not have the close loop system and the UNICHIP can maximise the efficiency of the car better, especially if u change the MAF and have some mod.....
There is a member in this forum who managed to squeeze 15hp from his E34 520i if i remember correctly....