(a) Agreed standards. The parties may determine by agreement the standards measuring the fulfillment of the rights of a debtor or obligor and the duties of a secured party under a rule stated in section 336.9-602 if the standards are not manifestly unreasonable.

(b) Agreed standards inapplicable to breach of peace. Subsection (a) does not apply to the duty under section 336.9-609 to refrain from breaching the peace.