WRX 04 - are there visual differences between PPP and stock ecu?
 

Is there any physical difference between them? Other codes, different stickers, etc.?
I need to prove to the insurance company that I have it installed. If there were some other numbers etc., I could just take a photo of it.
If there is no visual difference, maybe you have any idea how can I prove that it's different from stock ecu? (I have also silicone y-pipe, but no 3rd cat delete)

I suppose that I have this kind of ecu: https://www.ebay.co.uk/itm/Subaru-Im...kAAOSw~uJbRiJe

A PPP'd car would normally have a PPP certificate if official Prodrive upgrade.

https://img.pistonheads.com/LargeSiz...3463200-10.jpg


The ECU would have a code written on it similar to the one in your link as it would have been sent back from a Dealer to Subaru/Prodrive for flashing.
The Prodrive second cat delete pipe has brackets on it so that the original cat shields can be refitted making it look like OEM ??
Rear silencer ??

MY03/04 WRX PPP.pdf

Only real way to tell is to put it on a rolling road and compare figures to standard.

Unfortunately, I have mine wcu re-fitted from some other car that was originally a PPP WRX, so I have no Prodrive certificate.
By code on the ECU you mean this hand-written code (permanent marker)? I think that the insurance company will not take it as a legit evidence :P (anyone could write it down by hand).
So unfortunatelly, I think that dyno seems to be the only way to prove it.