Ecu & crap

Well im plannin to move to a 2g turbo ecu and so im pokin around to see what else may have to be swapped with it.

There are 2 boxes I want to know if anyone knows exactly what they do, and if they are used with the 2g turbo ecu (from people who actualy did the swap)

MR161489 : Fuel Consumption Control Unit
MB903862: Speed Control Unit

Now If I had to take a guess, id say the speed control unit is used with cruise control?

Fuel consumption unit is that thing that Craig n some others were talking about that regulates the pump voltage when its not needed at full power or something along those lines??

Any help is appreciated =D