I was really impressed with how well this combination came together utilizing the US EJ20 heads and a set of good cams.

I’m a pretty conservative tuner when using the dyno as I understand how much can change in the real world. At peak power the AFR was 11.1, boost was 19 psi, and ignition timing was only 18 degrees but the results were pretty spectacular. Spool up was also great as 18 psi was realized by 3600 rpm.

Given these results I think many should consider going this route instead of the AVCS JDM heads or the US STI heads.

I would definitely say if AVCS was not going to be utilized the better choice is putting cams in the WRX heads but it's so easy to run AVCS with the Hydra EMS. At this power level I can't tell you definitively what heads flow better but I'm leaning towards the WRX heads with cams. This is mainly based on the boost level, ignition timing, and AFR run on this car to achieve this power level as it compares to an STI with the same turbocharger. On an STI I usually see about 350 whp at 19 psi vs. 380 whp on this car.

Thanks,

Phil Grabow

www.elementtuning.com

Source:

WRX25 with EJ205 Heads Kelford cams

http://www.elementtuning.com/WRX25withEJ205HeadsKelfordcams.htm