With all of those gradually-improving power-bumped special edition Subaru WRX STI models out of the way now, the next step is the upcoming next-gen which will reportedly get a heavily overhauled Boxer engine making nearly 100 horsepower more than the current base STI.

News of the alleged new powerplant comes from of all places:

Subaru’s mighty flagship sports car, the WRX STI, is destined for a major upgrade come 2021. Sources close to the Japanese automaker tell us that the next generation WRX STI will employ an all-new 2.4-liter boxer turbo, called the FA24, pumping out no less than 400 horsepower and 361 lb-ft of torque.

By comparison, the 2.5-liter Boxer four-cylinder engine found in the makes 310 HP and 290 lb-ft of torque. Here are the supposed changes to the FA20 Boxer engine to get those significantly improved power figures for the new car, again from Forbes:

According to our source, the reworked FA24 in STI spec will employ a reinforced crankshaft and pistons, optimized timing balance, fine-tuned valves and intake ports, boost pressure will be tweaked and brake capacity will be enhanced, among other modifications. And married to the brand’s tried and proven symmetrical full-time 4WD system, expect nothing less than class-leading performance and handling.

It wouldn’t be too much of a surprise to hear Subaru is going with the FA24 for the new STI.Jalopnik contributor Bozi Tatarevic called it all the way . A version of the engine is currently in the 2019 Subaru Ascent SUV where it’s turbocharged and makes 260 hp and 277 lb-ft of torque. It’s also in the Legacy and Outback now, as well.

Looking at the current numbers for those FA24 engines, many worried Subaru wouldn’t push the next-gen STI too much further than the output of the current car. But if the Forbes report is true, clearly we have nothing to worry about.

Forbes also reported the alleged benchmark for the new STI’s engine is a Mercedes-AMG motor, the turbocharged 2.0-liter making 416 HP and 369 lb-ft of torque found in the .

For the last few years, we’ve had to simply make do with 300 to 350 horsepower as the expected gold

For comparison, the 2019 Subaru WRX STI S209, the most powerful STI ever sold in America (and also the most expensive), makes 341 HP and 330 lb-ft of torque, and is .

The U.S. government has finally allowed STI—Subaru’s elite squad of performance engineers—to build…

As for looks, the Forbes article doesn’t mention much but we can probably assume we’re going to get something with looks between the sharp concept car and the new we won’t be getting in America.

Subaru showed off the new Subaru Levorg STI Sport concept wagon at the Tokyo Auto Salon and if…

No word from Forbes about the . But whoever is involved and whatever it looks like, I like the idea of a bunch of 400 horsepower Subarus on the road.