The first Subaru Impreza WRX STi came out in January of 1994 and produced 250 horsepower. Later than year in November “RA” version was released with 275 hp and in August of 1995 second iteration of GC8 chassis came out and regular STi produced same 275 hp. Back then they were real monsters and could keep up with much more expensive supercars however since then 25 years have passed and modern Subaru WRX STi is just about as fast as the model released quarter century ago.
Whereas STi performance has stagnated, competitors over these years have become much more powerful. For example EU spec 1994 BMW M3 produced 286 horsepower – pretty much the same as STi, even more, the 1994 BMW M3s sold in North America produced only 240 horsepower – 12.7% less than STi of that same year which is considerable difference. The latest BMW M3 whos production ended 2 years ago produced 450 horsepower and a new model is about to come out with a power output of around 500 hp. As power output has stayed pretty much unchanged for STi, competitors have doubled their power output.
While in 90s STi could keep up with supercars, nowadays there are regular family sedans that are much faster. The lack of progress is very depressing for Subaru lovers (I know this because I’m one of them and used to own JDM STi years ago).

However it might change soon. Reports say that next generation Subaru WRX STi might use 2.4 liter boxer engine codenamed “FA24” with a power output of around 400 horsepower – still not enough to keep up with old rivals but a long awaited increase in performance is more than welcome.
Rumors are Subaru are benchmarking their new engine against the 2.0 liter turbocharged inline-four (M139) found in AMG models A45 and CLA45. M139 output 420 metric horsepower.
However we shouldn’t get our hopes too high. In the past there have been reports about significant power increase of WRX STi too and they have turned out to be false. However this time Subaru really needs for this to happen – performance of WRX STi in 2020 is just embarrassing and Subaru needs to act quick to make their sports car desirable once again!