Road and Track recently put the 2015 Subaru WRX and the 2015 WRX STI through a battery of dyno tests to find out not only how much difference there is between their two engines, but what kind of differences there are. The WRX gets the company's new FA20 2.0-liter boxer four-cylinder engine with features like a twin-scroll turbocharger, direct injection and variable valve timing on its two cams. The WRX STI stands pat with the older EJ-Series motor, meaning a 2.5-liter boxer four-cylinder with port fuel injection and carryover turbo lag. Subaru pegs the $26,295 WRX at 268 horsepower, 258 pound-feet of torque and an "extremely conservative" 0-60 mile per hour time of 5.4 seconds. The $34,495 STI clocks in at 305 hp and 290 lb-ft with a 0-60 mph time of 5.1 seconds. Ok, fight.
R&T's dyno runs sussed power numbers at the wheel of 223 hp and 245 lb-ft for the WRX, 247 hp and 243 lb-ft for the STI, then went on to demonstrate in numbers what everyone knew: that the WRX consistently puts out more of its torque earlier than the STI and achieves full boost almost three seconds quicker. On the other hand, on the track, the STI was also shown to have a conservative official 0-60 mph time, stopping the timer at 4.8 seconds compared to the WRX's 5.2 seconds.
The mag says it has comprehensive results coming from its "complete battery of tests," but for now, you can scrutinize their dyno charts and let the battle continue about which one you'd rather put your money down for.