I just installed a 1/4" smaller pulley on my whipple. It is supposed to give me 8psi. Well, it does, but only when i'm going about 80mph or so. Otherwise, it feels weak while accelorating and I'm getting knock retard of up to 6. I also am now getting 02 sensor codes again which I haven't since I got my most recent tune from Allen. What is causing these problems and is there a way to remedy them or should I just put the stock pulley back on?