i can tell you just that IMO these boxes were not conceived for older than let's say 5 year motors or high mileage ones, i've had one on mine(good brand not cheap one) few years ago when i knew less about D2s or engine management and after around 1 year i had to replace all 5 injectors with new ones, didnt have an EGT gauge at that time so maybe the cracked head later was a result of that too ... the cylinder balance which was good before went completely out of limist and the ECM was full of ''injector peak charge long'' fault codes... which after some research i found normal for the way these boxes are acting... afaik all these kind of boxes are involved only in the injector management by keeping them opened more to gain power but the original addaptive strategy of the ECM which is based on various sensor inputs will be completely mixed up... they can noticeably improve the driveability but IMO shorten the life of the engine on a long term usage... i won't recommend such thing for an already ''tired'' engine... on a second thought, i dont recommend them at all
