Having a second 4x160 seems to be a bit overkill to me. Do you really need the control that the 4x160 offers or could you get away with a single speed pump. BTW, why do you need the second pump for flow rate?
Also, when pumps are run in parallel, both pumps experience the same head loss caused by both flow rates. So this means that both pumps will be running under fairly high suction head but the return head would be approximately the same as if running alone. This can cause some problems if the suction head gets too high and may even cause cavitation.
You would be better off running each pump off it's own suction port and then recombining the returns right at the line that goes to the jets. Each pump would then be a bit more balanced for suction and return head. Return head will be high, which is ok and suction head would be much lower. This would prevent any possibility of the cavitation. This would also allow you to go with a much lower HP second pump since you will have both pumps delivering flow to the jets. It would also allow you to go with a single speed pump for the second pump but you would still have the control of the original Intelliflo so you could adjust the strength of the jets with the Intelliflo. However, because of the higher pressure of the parallel pumps, you would need to find a high head single speed pump to use that matches the Intelliflo.