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air/fuel ratio

  1. Engine Modifications
    So I have 2.5 inch equal length headers and up, the stock turbo, and a 3 inch catless tbe. Also a 3 inch cai and perrin turbo inlet on my 04 wrx. Never had any problems till recently. My afr's are suddenly running at 14.7:1 from idle tapering to about 12.8 at 3500 rmps and at about 4000 it drops...