Valuation of 2-4 unit multi-family: Income considered?

[Broderick Graham]

A real estate agent who has her own portfolio just sent me a listing for a triplex and mentioned that by raising the rents we could substantially raise the value of the property.

My understanding is that a 2-4 unit multi-family is valuated based off of comps alone.

Can anyone verify that amount of income for a 2-4 unit multi-family property is factored into the official value that an appraiser would send to the bank?