As part of last year’s Ward’s 10 Best Engines competition, we tested Subaru’s 2.0L “FA” turbocharged boxer when it was new in the Forester, so why are we evaluating it again?

Because it now makes an extra 18 hp in the sporty '15 WRX and features lots of fresh content intended to extend the performance envelope, including new camshafts, valves, rocker arms, cam sprockets, alternator, ignition coil and electronic controller. Plus, valve springs have been re-engineered to accommodate higher revving.

In addition, the WRX engine now redlines at 6,700 rpm (with 6-speed manual transmission), instead of 6,000 rpm in the Forester. And the torque peak lasts longer in the WRX – from 2,000 to 5,200 rpm, instead of 4,800 rpm in the Forester. The changes allow the WRX to develop its peak power using 15.9 psi (1.09 bar) turbo boost, rather than 17.1 psi (1.17 bar) in the Forester.

The boxer in the Forester wasn’t bad last year, but in general the class of 2.0L turbocharged 4-cyl. gasoline engines left us a bit disappointed, if you recall. Not a single one made the list, even though we tested seven of them.

This year, once again, we have seven new or improved gasoline 2.0L turbo-4s among the 38 nominees to evaluate, and a number of them, including the WRX boxer, are drawing solid reviews from the judges.

Stacking up the WRX to last year’s Forester, the little rally car is 355 lbs. (161 kg) lighter and $6,500 less expensive. It sounds much more emotive, thanks to a new exhaust system that eliminates one chamber in the muffler and shortens the internal tubing. The giant scoop on the hood pulls in more air to help the intercooler do its job.

But the key elements from last year’s Forester application carry over to the WRX, including bore and stroke dimensions, compression ratio, direct injection, twin-scroll turbocharger and Dual Active variable valve timing on both intake and exhaust valves.