On my last fiesta here in SoCal on 91 I would get knock around 20psi on the stage 2 setup. Went with ngk 1 heat range colder and was able to see 20.5psi and 21 on occasion with less knock. Stratified sells e30 tunes and I highly recommend their tunes if you want more performance, earlier boost, 25psi even in the heat, and a cheaper tank of gas.
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