Can some one tell me. when you decat your exhaust to gain more power, do you get a light come on on your dash as the ecu has detected something wrong with emistions etc. If so do you have to re programme your ecu to get rid of this light, also if you have to reprograme your ecu does this effect your immobliser in anyway? And one last question can you just plug a modded ecu into your motor and enjoy the extra bhp with no downside, ie does everything work as normal Thanks for your help

 

Depends what year

 

Ive got an 04 plate sti and was wondering if i could get a reprogrammed ecu could i just plug it in add a few mods ie exhaust and fuel filter and enjoy the extra bhp