It started its life for the 9/98-8/99 GC8 in Japan, UK, Australia.

The EJ207 has an 8.0:1 compression ratio.

To identify a 9/98-9/2000 EJ207 (v5/v6 WRX STI GC8/GF8)
wasted spark coil pack off center of manifold
idle air integrated into throttle body
inlet under manifold
red or bare aluminum intake manifold
Open deck block (2001+ are all Semi-closed)
higher rev limit than ej205
Version 7 has AVCS
V7 are single scroll, AVCS, throttle by cable, top-feed injectors, engines.

The TGV are deleted from the factory.
The factory deletion is incomplete, even on the Spec C and even on the Type RA.

The exhaust is compatible all the way to the downpipe to the USDM WRX/Sti.
Oxygen sensor is same as USDM EJ205.

The oil pan is like the USDM WRX 2.0
The Turbo is the VF30.

The ECU has the same number and shape harness plugs as the USDM WRX 2.0.

No immobilizer.

The engine speed is limited from the factory at 8000 rpm
V8, 9 are twinscroll, AVCS, throttle by cable, topfeed injectors, engines.

There are no TGV's, the intake manifold is one piece.

The spark plugs are specified one step colder, compared with other Sti.

The exhaust is completely different/incompatible with the USDM WRX/Sti, all the way from the header to the downpipe.
It can be replaced by a USDM exhaust, the USDM does bolt up to the block.

The oil pan is like the USDM Sti.

The turbo is a VF37.

The ECU has the same number and shape harness plugs as the USDM WRX 2.0
There is no immobilizer for V8 and for some V9.
Although to some V10.
Even more from imported models.
There were no transponder chip's inside the transmitter housing case.

The V9 known so far to not have immobilizer have been early V9 Spec C (revision E engines).

The engine speed is limited from the factory at 8000 rpm
When compared with the USDM A/C compressor, the JDM Sti is of a different part number and smaller in size.
It is possible that the losses while using it are smaller.

Many have an additional intake air temperature sensor by the throttle body.
Its function has been discussed but not completely clarified.

The power steering pump is different.
The JDM cars included some Spec C with 13:1 steering rack.
The pump remained the same, so it is designed to handle a fast rack.

The com protocol is not canbus for any of these.

Some of the Sti engines don't come with provision for cruise control.
It is next to impossible to tell which had it.

The ROM settings are quite different from a V7.

The turbo inlet has one less connection in it and most likely is of a larger diameter than the USDM, from the factory.

The front Oxygen sensor has been relocated after the turbo, in the downpipe.
Different part number 22641AA042.

Usage:
Impreza WRX STi 1998~present (JDM, specifically homologation models for World Rally Championship)
It started its life for the 9/98-8/99 GC8 in Japan, UK, Australia.
The EJ207 has an 8.0:1 compression ratio.
To identify a 9/98-9/2000 EJ207 (v5/v6 WRX STI GC8/GF8)
wasted spark coil pack off center of manifold
idle air integrated into throttle body
inlet under manifold
red or bare aluminum intake manifold
Open deck block (2001+ are all Semi-closed)
higher rev limit than ej205
Version 7 has AVCS
V7 are single scroll, AVCS, throttle by cable, top-feed injectors, engines.
The TGV are deleted from the factory. The factory deletion is incomplete, even on the Spec C and even on the Type RA.
The exhaust is compatible all the way to the downpipe to the USDM WRX/Sti. Oxygen sensor is same as USDM EJ205.
The oil pan is like the USDM WRX 2.0
The Turbo is the VF30.
The ECU has the same number and shape harness plugs as the USDM WRX 2.0.
No immobilizer.
The engine speed is limited from the factory at 8000 rpm
V8, 9 are twinscroll, AVCS, throttle by cable, topfeed injectors, engines.
There are no TGV's, the intake manifold is one piece.
The spark plugs are specified one step colder, compared with other Sti.
The exhaust is completely different/incompatible with the USDM WRX/Sti, all the way from the header to the downpipe. It can be replaced by a USDM exhaust, the USDM does bolt up to the block.
The oil pan is like the USDM Sti.
The turbo is a VF37.
The ECU has the same number and shape harness plugs as the USDM WRX 2.0
There is no immobilizer for V8 and for some V9. Although to some V10. Even more from imported models. There were no transponder chip's inside the transmitter housing case.
The V9 known so far to not have immobilizer have been early V9 Spec C (revision E engines).
The engine speed is limited from the factory at 8000 rpm
When compared with the USDM A/C compressor, the JDM Sti is of a different part number and smaller in size. It is possible that the losses while using it are smaller.
Many have an additional intake air temperature sensor by the throttle body. Its function has been discussed but not completely clarified.
The power steering pump is different. The JDM cars included some Spec C with 13:1 steering rack. The pump remained the same, so it is designed to handle a fast rack.
The com protocol is not canbus for any of these.
Some of the Sti engines don't come with provision for cruise control. It is next to impossible to tell which had it.
The ROM settings are quite different from a V7.
The turbo inlet has one less connection in it and most likely is of a larger diameter than the USDM, from the factory.
The front Oxygen sensor has been relocated after the turbo, in the downpipe. Different part number 22641AA042.
Usage:
Impreza WRX STi 1998~present (JDM, specifically homologation models for World Rally Championship)
Subaru EJ engine