Is it a Bugeye, or maybe just after? Around 2001-2003 there were a few cars badged as a "WRX" that had the bucket seats, flared guards, but no turbo. I'm pretty sure it's factory badging...
Yeah the JDM bugeye wrx came in either an ‘NA’ or ‘NB’
The NA was a non turbo wrx similar to the srx of the gc8 era. As boon said it had better seats, wrx struts and maybe a couple other upgrades but yeah the non turbo bonnet with wrx badging was a factory thing.
Edit: http://a15ff11300g.sakura.ne.jp/catalogue/GD.GGimpreza/2000.8 new age impreza WRX/2000.8 new age impreza WRX.html
That'll be what I was thinking of then I knew one of them advertised a STI tune as well.
That's the classic hesitation most of us have had. The easy fix is to swap the vac lines for the BPV and the fuel pressure reg so that the reg gets it’s source from the centre of the manifold and the BPV can use the one on the cylinder 4 runner. The one by cylinder 4 fluctuates a bit with valves opening and closing constantly so moving the vac reference to the centre seems to help the situation sometimes.
This article mentions it can cause AF correction one to be off but towards positive rather than negative like yours is.
https://www.cobbtuning.com/2008-sti-fuel-pressure-regulator-kit-update-technical-overview/