My MY97WRX has an HKS Induction kit on it, which was there when the car came from Japan. I had a PE Phase 1 conversion done after leanness was found after decatting. I was told that the injectors were running at around 96 - 97 % duty cycle just to get enough fuel to run safely. After recent problems and mods, I am having my car remapped by Pat at Subaru4You on Monday (some spaces available if anybody is interested) because PE no longer offer the service, and was wondering if there would be any benefit in reinstalling a standard air box with a panel filter. I'm sure this would allow for lower injector duty cycles, but could this be used to get more power? or am I best sticking with the HKS and making a cold air feed?.

Other mods fuel wise include a Walbro 255l/hour pump, fse adjustable regulator feeding standard 440's.
Thanks.