Thanks for replies.
@MiRaGe, do you have a B18C6, right? So spoon sump is identical to OEM, but have some baffles inside. In this case, it should fit a B18 with OEM sump as well.
It's a little bit strange, on Tegiwa site it is said that fits "B16A only" and on Skunk2 site it's "for B series"...