My car is a 05 wrx ppp,I've got a Hayward & Scott full decat exhaust with the cell-fix (wire in the ecu) to stop the engine light coming on. I want to buy a decat uppipe from somebody like Harvey but I'm not sure if this will effect the engine light. Can somebody explain about egt's and resistors to me in simple terms? Cheers, Mick.

 

Pretty sure there's no cat in the later newage WRX's.
If I'm wrong I'm sure someone will correct me shortly.
Wes

 

I think there is a cat in the uppipe

 

Definitely is in the bugeye WRX's, but I don't think there is after that chap.
Wes