Attn: Grease Monkey or anybody technically knowledged
 

I just purchased a full Jap Spec STI8 exhaust system for my 03 WRX and wanted to know if it will invalidate my warranty??

I dont think you need to be technical to answer this one.

Yes, it'll invalidate your warranty.

Unless a part is supplied and fitted by Subaru or Prodrive they'll use it as an excuse if something goes wrong.

But ...
 

Is it a UK 03WRX?

Do you mean aftermarket Jap Spec STI8 exhaust system or Subaru OEM Jap Spec STI8 exhaust system? If the latter then it could be more interesting than suggested by UHF.

No doubt they would still use some guff about how its a UK car with a Jap part and therefore falls foul of the warranty.

From what i understand about warrenty, anyhting fitted outside of Subaru affects the warrenty... :(

Just arguing with Subaru on my AP Racing brakes.

If they dont like them they get replaced!