I currently got P2 flash and wanted to switch to utec, do I have to reflash my ECU back to stock? Or can I combine it with a UTEC?

 

You can run the UTEC with the flash, but some users have had issues running with both, others haven't had any.

If possible you should reflash the ECU back to stock.. If you can't, then you can work around it, but all of your maps and some of your parameter adjustments may be different than some of us with stock ECUs..

 

Get the P0300 flash at mitsu, look at my "Just installed" thread