Hardcore Subaru fans could argue for days on end about which variant of the WRX STI is the greatest of them all. The legendary GC8 Impreza 22B is sure to be one of the first to be discussed, with others within a shout, including the early Type RA, the GD Spec C RA-R, and the UK-only Prodrive Impreza P1.Whichever comes out on top of all the special variants will depend on who you ask, what time of day and the mood they’re in. Objectively, though, there’s only one ‘ultimate’ line of WRX STIs in the eyes of the manufacturer itself, the fabled S Series.These models were honed by Subaru Technica International to be the best they could possibly be, with each generation of the WRX STI so far receiving an S-badged variant. Here’s a breakdown of them all. Subaru Impreza S201 Via: Larry Chen on YouTube Subaru Impreza S201 Specs At the end of the GC8 Subaru Impreza’s production run in 2000, STI set to work on making the most track-focused variant of the turbocharged hero to see it off. The result was the first S model, the Subaru Impreza S201.Based on the four-door variant (for reasons unknown) of the Impreza WRX STI, it was the first Impreza to be officially exempt from the Japanese Gentleman’s Agreement, which capped power at 276 horsepower from the factory at the time, owing to its status as technically being an aftermarket vehicle.The S201 produced 300 hp from its EJ20 engine, owing to a new ECU and uprated intake system. Suspension stiffening came courtesy of rear full pillow lateral and trailing links.Most obvious of all the changes, though, was the bonkers fiberglass bodykit with extended bumpers, wider side skirts and the gigantic triple-decker rear wing. 300 were initially set for production, but just 87 examples are believed to have been built, and all for Japan, as almost every car on this list (bar one) was.Although now legal for US import (and the only model on this list to hold that status at the time of writing), finding one of those examples won't be an easy task. Subaru Impreza S202 via youtube Subaru Impreza S202 Specs Two years on from the S201, just before the GD Impreza facelift taking the model from ‘bugeye’ to ‘blobeye’, STI engineers decided to give the polarising follow-up to the original WRX STI its own S version.As with its predecessor, the Subaru Impreza S202 used an EJ20 engine but here producing 316 hp, with additional power liberated by a titanium muffler, a further updated intake system and a reworking of the car’s ECU. Its suspension setup also had uprated trailing links, while forged aluminum wheels aimed to reduce unsprung mass.The styling of the S202 was much tamer than the S201, with a slightly reworked front bumper and an adjustable carbon fiber rear wing. 300 were built in 2002, and will be eligible for US import from 2027. Subaru Impreza S203 STI Subaru Impreza S203 Specs With the GD Impreza once again receiving a facelift from ‘blobeye’ to ‘hawkeye’ in 2004, STI again set about giving the model another S series version. This time, the S203 could’ve had an easy template to follow by using the chassis of the S202 with an updated look. That simply wasn’t the case, though.Its peak power figure was the same on paper, but STI opted to fit a larger turbocharger and undertake engine balancing for the Impreza S203, leading to a higher torque figure. Stiffer dampers were fitted, along with thicker anti-roll bars. More aggressive bumpers came here, too, along with a new carbon fiberrear wing.555 examples were built, making it marginally less rare than the two cars that came before it. Notably, Subaru World Rally Team driver and 2003 World Rally Championship winner Petter Solberg had a hand in this car’s development. Subaru Impreza S204 STI Subaru Impreza S204 Specs At the very end of 2005, just under a year after the S203 went on sale, STI once again decided to revisit the GD Subaru Impreza WRX STI for an S Series model. This time, it took development outside of Japan for the first time and honed the model in the UK. An interesting decision, given it remained a Japan-exclusive car.The rest was a more performance-focused suspension setup with dampers different from those on the S203 and additional pillow bushes, while standard-fit uprated Brembo brakes helped improve stopping power.Engine development went further with an even larger turbocharger and a decision to manually measure pistons and con-rods before installing them into the block for more precise engine construction. Peak horsepower from the EJ20 remained the same, but it gained more torque than the car that came before it.Rounding out the package were 18-inch BBS wheels, a carbon fiber front splitter and a new rear wing. 600 were made, though it’s likely the most recognizable of the early S series Imprezas to American enthusiasts, owing to appearances in the Forza Motorsport video game series. Subaru Impreza R205 STI Subaru Impreza R205 Specs If the GR Subaru Impreza WRX STI wasn’t already enough of a departure with its hatchback body style, STI went a step further in branding the most special version it made as an R205, rather than sticking to its nomenclature. Slightly infuriating for the pedants out there, but the recipe was similar to those that came before.Once again using an EJ20 with an officially quoted 316 horsepower and with torque identical to the S204, the biggest change to the engine was a new ball bearing twin-scroll turbocharger. It was arguably the tamest looking of the lineage yet, with a subtle extended rear wing and a small front splitter. Its biggest chassis change came in the front of a new ‘Flexible Draw Stiffener’ fitted alongside the STI suspension setup to improve stiffness. 400 were made in 2010. Subaru WRX STI S206 Subaru Subaru WRX STI S206 Specs With the return to a saloon for the GV WRX STI, the special version reverted to type with S206 badging.The enhancements seen on the R205 were carried over to this model, although it did gain 19-inch BBS alloy wheels as standard, with 300 made in 2011. Most exciting, though, was the optional ‘NBR Challenge Pack’, designed to celebrate a WRX STI winning in class at the 2011 Nürburgring 24 Hours. This brought a carbon fiber roof and rear wing, with only 100 of these variants available. Subaru WRX STI S207 Subaru Subaru WRX STI S207 Specs Subaru’s presence at the Nürburgring would go on to influence S series models further, with the arrival of the VA S207 in 2015. Still using an EJ20, official peak power was increased for the first time in over a decade, owing to a reworked exhaust system and revised ECU.New Bilstein dampers came to the front axle, while an extended carbon front splitter was added. Once again, an NBR Challenge Package was available, this time making up half of the 400 S207 units built. These were painted in an exclusive Sunrise Yellow and gained a large rear wing. Subaru WRX STI S208 via CNET Subaru WRX STI S208 Specs Two years on, STI would revisit the VA WRX STI with the S208. Changes over the previous model were very restricted, with the introduction of a carbon fiber roof the only significant difference. That would be left unpainted on cars equipped with the NBR Challenge Package, which made up 350 of the full 450 production run. Subaru WRX STI S209 Via Automobilemag.com Subaru WRX STI S209 Specs At the end of the life of the VA WRX STI, and seemingly, the performance model it’s based on, Subaru made a huge change to its S series model.For the first time, you could have it in North America, and only in North America. No, the WRX STI S209 was not sold in Japan, making it the only model in the whole S series run not available in Subaru’s home market.As a result, it used the 2.5-liter EJ25 rather than the JDM EJ20. It was the most powerful model in its lineage, gaining a boost over the regular USDM WRX STI thanks to a high-flow intake system, a larger turbocharged, reworked ECU and a high-performance exhaust system.19-inch BBS wheels were standard, and complemented the extended front splitter and huge rear wing fitted to the S208. A carbon roof was used to reduce the center of gravity, while additional suspension stiffening came from components taken from Subaru’s Nürburgring race car. 209 examples were built, retailing from $63,995 on its launch in 2019. Subaru WRX STI S210 Subaru Subaru WRX STI S210 Specs With production of the Subaru WRX STI ending in 2021, it would’ve been fair to assume that would be it for the S series models. Only it wasn’t, with STI surprising us all in 2025 with the arrival of the Subaru WRX STI S210.Based on the VB WRX, the S210 featured extensive updates to that car’s 2.4-liter turbocharged boxer engine. Those include a new intake system, an uprated exhaust and an ECU tune. Despite that, it goes down as the least-powerful S series model since the original S201 25 years earlier.Disappointingly, it used a CVT as well, despite every model before it coming equipped with a manual gearbox.It did get some extensive chassis changes, though, including retuned adaptive dampers, larger Brembo brakes and additional stiffening. 500 were made, and with a return to Japan exclusivity.