i have a n reg wrx and have the ecu from a sti ra m reg , can i just plug it in or do i need to do other things first??

 

You can just swap it over (you can disconnect the battery if you want).
What ecu is it (i.e. what code has it on the cover SB possibly?).

 

yes m8 sb in pink writeing , will it make a differnce its been re mapd the subaru it came out of was pushin about 380 - 400 bhp so am hopein it will make sum sort of difrence.

 

well unless you've got all the mods to make it run that power it won't make it in your car
How was the ecu remapped as the early ones need an extra chip or daughterboard (if it's a remappable daughter board that's cool as you can have it remapped for your car).

The standard SB does run quite lean though.