2004 Subaru STi GDB Part 1

The Dyno

DSPORT Magazine Test & Tune of the 2004 Subaru STi GDBBaseline

Strapped to a Dynamic Test Systems 4-wheel dynamometer, the stock STi generated 264 horsepower at the wheels. That’s aobut a 9-percent advantage on an EVO-VIII.

244.4 WHP

Dynamic Test Systems Dyno


DSPORT Magazine Test & Tune of the 2004 Subaru STi GDBTest 1 INJEN Cold Air Intake

Power was increased in all points in the graph and significant gains began to appear at about 5,200 RPM and beyond. Gains were as high as 11 horsepower and peak horsepower jumped by almost nine horsepower.

273.2 WHP @ 6,707 RPM


DSPORT Magazine Test & Tune of the 2004 Subaru STi GDBTest 2 MagnaFlow Ti Exhaust

The MagnaFlow exhaust also delivered gains from start to finish. Gains were as high as 11 horsepower with the peak horsepower being pushed up nearly seven additional horsepower.

280.0 WHP @ 6,047 RPM


Strapped to a Dynamic Test Systems 4-wheel dynamometer, the stock STI generated 264 horsepower at the wheels. That’s about a 9-percent advantage on an EVO-VIII. We then installed the Injen intake and we were quite happy with the results. Power was increased in all points in the graph and significant gains began to appear at about 5200rpm and beyond. Gains were as high as 11 horsepower and peak horsepower jumped to 273.2 ponies. With significant power increases resulting from the Injen intake, we were excited to see what gains the MagnaFlow exhaust would deliver. Once again, we were very impressed with the results. The MagnaFlow exhaust also delivered gains as high as 11 horsepower with the peak horsepower being pushed up by 6.8 horsepower.