Did you read the "safely modding your 3800" thread?


First things wrong, 04+ should not run 160* Tstat (that's even on the product page on ZZP) and 103's are going to be a stage colder than your want for just a 3.4 pulley and a pcm.

Second thing that's wrong, You're on a 3.4 with just a zzp PCM. ZZP PCMs are known for running lean which creates knock. Where are the supporting mods for the 3.4 pulley?

Get a wideband! It will help dial in your fuel trims when you get a tuner.