TurboTwin

After the fuel pressure regulator was swapped to an 07 sti style with new lines, 90% of the problem was gone. There is still a flat spot at just about 2500 rpm, but only at certain part throttle conditions. I have not had the retune done yet, so I still hope that may cure it, but I will let you know. I would say that if you do the FPR and lines, you should reset the ecu after that, to clear any learned 'bad habits' the car had before the change.

I wanted to report that I had severe stumbles in the 2000 to 2500 rpm range. I changed the fuel pressure regulator to the 2007 STI setup, and this cured my problem. It is so much smoother, more power all over. I would say it is 90% cured. I will now have a final tune by Dave of cryotune, and let you know the results after that. I wish I had done this change years ago. My car is a 2005 LGT 5spd Wagon, with stock turbo, custom tune, up pipe, downpipe, intake and rebuilt engine with forged pistons. Thanks so much to the people that figured this fuel pressure issue out, and posted it here.

I have an 05 LGT with the same studder stumble between 2200-2500 rpm. I looked at the stock FPR setup, and wonder if I can just replace that with the other Subaru FPR part no. 22670AA351? Do I need to change the fuel lines in the area to use that part? Is it really the FPR change that fixes the studder? I have been custom tuning it with Dave at CryoTune, but we can't get rid of it. Thanks, TurboTwin.