What is needed to swap an e46 330xi engine into 325xi?

[VenomRS4]

So I may be acquiring a free 2003 325xi manual with a 170k miles. It's blowing white smoke and the head gasket was already done...so it may need a head. And I don't know the condition of the block. Instead if doing the head, I might just buy a known good engine...freshen it up and swap it in. And after looking into it... it seems like m54b30's are the same price as m54b25's. So that gets me thinking...what would be necessary to swap in a b30? That would be a nice power gain.

Anybody know what is necessary to do this swap? I'm sure ecu but what else?

Thanks!

[TerraPhantm]

Pretty much plug and play. You'll want the intake and maf from the B30 at minimum (3 liter intake is larger diameter). If the engine came from a non-xi (or non-E46) you'll have to swap the oil pans and maybe keep your original harness depending on exactly what the donor is. After that you just need to flash your DME with the b30 software.