UK cars;
Blobeye STi was availble on 03 - 55 plate and had the 2 litre engine
Hawkeye STi was available on 06 - 57 and had the 2.5 litre engine
The Hawkeye had a revised interior as well as the addiiton of the DCCD gearbox and wider rear track. The DCCD allows manual control of the torque placement (front/rear split) through a jog wheel in the car.
A limited run of very late Blobeye STis (05/55 plate) were a bit of a parts bin special and had the 2 litre engine alongside the Hawkeye interior and DCCD gearbox. These were known as the widetrack. If looking for a UK blobeye, I would definitely consider a widetrack over an earlier model.
All UK cars ran unequal length exhaust headers/manifolds and a single scroll turbo. They had the notorious Subaru burble exhaust note.
The 2.5 engine isn't as strong as the 2 litre and is more prone to piston ringland and headgasket issues.
VED is also much more expensive on 2006+ cars.
JDM cars;
All had the 2 litre engine, however this is slightly stronger and better regarded over the UK engine. Better internals, higher rev limit (8000rpm vs the UK 7200rpm) and easier to reach higher power figures when tuning. They did however use equal length manifolds and a twin scroll turbo which provided better throttle response but at the expense of the exahust note. It doesn't sound like a traditional inline 4 though and I'd say is more inkeeping with the sound of a Mazda rotary engine.
JDM cars had a few additional bits such as an updated dash cluster (power-on sweeping clocks) rear wiper, cruise control, auto water spray for the intercooler (UK cars were manual control) and electric folding mirrors. Some of them also had the DCCD. It only sounds like a couple of little extra bits but some UK owners will pay a premium for these JDM parts.
Definitely do not discount the JDM cars in your search! They are brilliant!!
One thing to watch for with JDM imports is that they are sometimes advertised as having had a full body underseal. I've seen some of these jobs in person and it tends to involve somebody spraying the entirety of the car in one fell swoop without removing anything. These are usually rush jobs where people are making the car look nice and fresh underneath, but at the expense of future corrosion issues!
All cars whether UK or JDM are now at an age where rust can be a real issue. Common issues are under the rear spoiler where it meets the edge of the boot (easy fix), rear arches, sill edges, rear strut towers (can be a big issue).
There are some nicely modified cars about, however if you'd rather a lower mileage unmolested example these do crop up. For a really nice UK car I'd be looking at spending around 15k. Up to 20k for a JDM car.
These cars are holding their money very very well though! I bought mine in 2017 and values have shot up since then.
will have a read through and take note!
not ready to buy one just yet