In the original post you said 8% cash on cash, which would mean based on however you bought. If you’re getting 16-17% cash on cash, that’s pretty damn good.
The cap rate should be based on today’s cash flow. Cap rate is a method of valuing current cash flow. If it’s worth more than what you paid (which by all indications, it is), then the effective cap rate would be less than your cash on cash return.