Salt-induced hypertension has been widely studied in rats, monkeys, chimpanzees and humans. Until recently, the multiple phases of this blood pressure increase to high salt intake had not been closely studied. This work builds upon a recent study, which developed a grey-box multicomponent model of salt-induced hypertension in the Dahl-S rat. The previous 3-component model has been extended here to include additional model dynamics to improve the model fit and add new important elements to the model response. The model was optimised using numerical techniques with experimental data from 4 different protocols with Dahl-S and hybrid rats. Results show a marked improvement over the previous model and confirm the merit of the 5-component model structure.