Eventually I will be dropping to a 3.4" pulley, but I want to get all the supporting mods first. Recently, I added a ZZP catted dp and it triggered my SES light. I was going to get the o2 emulator, but since I am going to be getting an overkill PCM very soon I figured I might as well just wait until I get the PCM because I can have Will at overkill remove the code. I will be getting the PCM before the 3.4" MPS and my question is will it be safe to run the stock 3.8" pulley with an overkill PCM tuned for a 3.4"?

Email Will and ask. He would know more than any of us.

I imagine you will be fine though as you're running a larger pulley than the tune is for.

Just wait.

You'll be fine. It won't have the best performance but it won't hurt anything.