No, the 1:1 NAT IPs go before the masquerade rule.
For example,
SNAT rule 5000 = source 192.168.1.150 / outside x.x.x.52
SNAT 5010 = S 192...151 / out x.x.x.53
SNAT 5020 = masquerade to x.x.x.51
For example,
SNAT rule 5000 = source 192.168.1.150 / outside x.x.x.52
SNAT 5010 = S 192...151 / out x.x.x.53
SNAT 5020 = masquerade to x.x.x.51