Same as in Figure 5, but for the SIGW-BOX model. The regions above the teal contour lines labeled f PBH = 1 lead to the overproduction of PBHs, according to our analysis in Appendix C.2; however, see text for more discussion. Figure 23 in Appendix C.2 shows an extended version of this plot that includes the SMBHB parameters A BHB and γ BHB.