A few weeks ago had a remap done to my subaru sti 2008 hatchback and was please with results, achieving around 330/340 bhp.
Was a huge difference in feel, but today the car feels less powerful and has some hesitations when accelerating hard,

Can anyone tell me if this can happen, should I do a ecu reset by disconnecting battery lead and pushing brake pedal down until it's reset

All your help is appreciated cus I'm a newbie and haven't got a clue about cars.....

 

Could be anything. Start by getting the error codes read (or do it your self ). A quick google found THIS.

 

Are you sure its just not down to the rise in temps with the weather we are now having,the car will not perform half as good as it should in hot weather mate.

 

Depends if the mapper can be bother to set it up properly mine was shocking in traffic and had to be remapped again with someone that could be bothered to spend a bit time on it.

 

Go back to the mapper. Is he a known mapper. If so it should get sorted

 

Who was the mapper?