Which number to use for PV on a financial calc

[Pari Thiagasundaram]

3 year Loan 33 months remaining. Payment of -$950.67 per month with UPB of $29000. Getting the note at a discounted price of $23000.

When i calculate my returns on a financial calculator, which one should be my PV ? (UPB or the discounted note price)

Reason i am getting confused is, i pay a discounted price for the note but the pay back is on the UPB. (Typical newbie question eh ? :P )

[Mike Hartzog]

I generally look at investment yield rather than IRR for notes. I get a yield of 23.317%, using 33 payments of 950.67 with a 23K investment. If you are using a servicer, you may want to find your actual yield by using an adjusted monthly payment which removes the monthly servicing charge, i.e., the net payment to you.