Both previous Aviva Premiership visits to Franklin's Gardens have ended in defeat for a team that has defied all expectations during their two-year spell in the top flight.
Hepher insists that facing title-chasing Saints will prove informative for a side that demolished Sale 43-6 last weekend.
"This will be a great challenge for us," said Hepher, who played 120 times for the Saints.
"They're obviously a top team - not just in the Premiership, but also in Europe as well and that's where we need to be testing ourselves.
"This weekend will give us a good gauge as to how good a side we are.
"We've been disappointed with our performances at Northampton in the past. That said, you have to credit Northampton as they have come up with some great performances.
"It's a tough place to go for sure, but that's all the better for us in some ways as we know we have to challenge ourselves at the hardest places if we are going to improve as a side."
Exeter are missing centre Jason Shoemark to injury so Phil Dollman steps into the midfield.
Northampton will go into battle with the same starting XV that secured a fine 24-19 victory at Gloucester last Saturday.
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