bone25

Hello, My ’03 Sti (type Uk) has had the following mods: APS 3” exhaust with sports cat. Uprated fuel pump High Flow Turbo Exhaust Discharge Cold air induction Ecutek re-map Since the re-map it hesitates and makes a fluttering noise between 3k and 4k revs when under load (it’s really bad in 5th and 6th gear). On the dyno the boost went up to 1.5bar at about 3500 revs and dropped gradually to about 1.2bar at 6500 revs. But recently I fitted a boost gauge and the boost only went up to 1.2 bar and then dropped suddenly to 0.8bar, it then fluctuates up and down until the hesitation stops. I have now fitted an apexi boost controller and the boost rises up smoothly to 1.5bar but the hesitation is still there? I’ve checked the plugs, coil packs, and air flow meter, they are all ok. I have also fitted a new dumpvalve. I’ve been back to the mapper but he said that it was compressor surge and this is normal. (I don’t believe him) Does anyone have any ideas what could be wrong? It’s driving me nuts!