Some of the older 2.2s had dual port heads. My 95 Legacy has them, and I think 95 was the last year for the dual port 2.2 heads. Not sure why they changed the design, as in my limited theory mind, it would seem more efficient to keep the heads dual port--what made them say "Hey, let's change the heads to single port"? Of course, my 99 EJ22 is rated with more hp than my 95 EJ22. Other than changing the sound of your exhaust tone, I really wonder if headers on a 2.2 with no internal mods would even do anything for hp/torque...