Yeah, that's how they always were. I never understood the principle behind it either but I remember that when the belt was correctly tensioned then I could see it move up to the middle of the pulley even if I just raised the car up and throttled up.
I assume you remembered to loosen the bolts before tightening the tensioning screws - otherwise you'll just bend the bar that goes through the front transmission housing!
Also check out Luke's thread
here. He has lots of pics and detail about how he modded the front gearbox with the bolts and spacers to help tension the belt. I know he's got the MMS diff but the mod works all the same.