I just went stage 2 on my 02 wrx about a week and a half ago.
I've noticed that between shifts after clutching, at about 3-4k rpms there is a slight rattle from the center of the car in front of me. Sounds like it is something central in the engine bay.
I have some other in car rattles, but this is clearly distinct.
Its been really cold lately, and I can't confirm that its been running much worse than usual, it just seems somewhat bogged down. Part of me thinks i may just be imagining a power loss.
anyways...does anyone have any ideas of what the problem could be? I've seen a few threads on the same topic, but havent gotten a legitimate answer or idea.
many people have said heatshields which i've checked and it is not.