Let's face it, the $8,000 premium for the Subaru STI over a standard Subaru WRX is a lot of money. What's more, some argue the difference in performance on the road between the STI and the standard WRX is only marginal. When the 2015 Subaru WRX STI claimed to have 305 horsepower, the boys at Road and Track invited a standard WRX and brought out a dyno in order to stage the following question: Yeah, but what does that translate to on the tarmac?
On paper, Subaru claimed the STI's 2.5-liter, port injected, turbocharged powerplant delivers 37 more horsepower (305 HP in the STI vs. 268 HP in the WRX) and 32 lb-ft more torque (290 vs. 258) than the standard WRX. In the real world dyno, Road and Track found a different story as well as a little more detailed information.
The standard WRX on the dyno managed 223 horsepower to the wheels at 5,800 rpm, while the WRX STI managed 247 horsepower to the wheels at 6,400 rpm. On the torque front, the standard WRX managed 245 lb.-ft. at 3,850 rpm, while the STI's output was 243 lb.-ft. at 5,000 rpm. Remarkably, the WRX surpasses the STI in peak torque, if only by 2 lb.-ft. What's more, Road and Track also found that the WRX reached its full boost in only 6.75-seconds, while the more laggy STI needed a full 9.5-seconds to get the full kick.
The little extra torque and the broader power makes the standard WRX a closer competitor than the $8,000 bargain suggests. The standard WRX stands to be a lot more useful on the road than the more peaky STI. However, if a track weapon is what you're looking for, then the rev-happy STI is the crazier and more demanding choice.