Shop: Maxwell Power Services
Location: Arlington, WA
Ambient Temp: About 50 degrees F
Elevation: 200 feet
Car: 2006 WRX
Dyno Info: Dynocom
Transmission: Stock 5-speed
Peak HP at RPM: 387 @6400 rpm (about 340 on a Mustang)
Peak Torque at RPM: 410.8 @ 3950 rpm (about 360 on a Mustang)
Baseline hp/tq for a stock Sti on same dyno: 245/245
Target Boost: 21.8 psi
Target AFR: 10.7
Fuel: 92 pump
Engine/Power Modifications: HTA68 with 10cm hotside installed by Dom, Helix catted downpipe, STi intercooler, Invidia Q300 catback, Gimmick inlet hose, 725cc injectors, Walbro fuel pump, APS Cold air intake, Agency Power UEL header, TGV deletes, Grimmspeed Uppipe, Prosport MBC for hybrid boost control.
Driveline Modifications: ACT street clutch
Suspension Modifications: Whiteline F/R swaybars, Stoptech stage 2 brakes
Tires: Federal SS595 215/45/17 on stock WRX wheels.
After my #4 ringland objected to 75k modded miles, I went with a Maxwell Power Factor SS EJ257 with some B25 heads. The block has JE pistons, H-beam rods, ACL bearings and is balanced/blueprinted. I also added some stronger springs and 264 exhaust cams, plus an Accessport so that Dom could do a speed density tune. A post-intercooler IAT sensor helps keep things safer.
The car's last tune (and the very last for the previous motor) produced 371hp at 5900 and 400tq at 3950. The new build has noticably more kick up top. Dom did the pull up to 7500rpm, but you can see there's not much point in holding it that long, except that in first gear I no longer bounce off the limiter (now set to 7700) and the extra headroom puts the shift to 2nd in a very good place.
The powerband is pretty good -- over 350hp/tq for almost 4k of range.
It will be fun to go bigger in the future, but the next upgrade, someday, will have to be the tranny.