can i use a later ecu in my v3 sti
 

like a V5/6 sti ecu or a P1 ecu as they can be remapped cant they ?

whats the difference if i did ?

I don't believe it is possible.

TBH by the time you've bought an ECU and paid for the re-map, you might aswell go for an Apexi Power FC or Simtek anyway :thumb:

the price of a power FC mapped aint gonna be cheeper than a chipped ecu from a v5 or P1

its technically less hassle i agree but theres another reason why im asking

Not with out the loom and most of the engine.
Cheaper to go aftermarket management.
The sti3 engine is pretty good and will see a nice power increase