Haw. Rev. Stat. § 490:2-202: Final expression: parol or extrinsic evidence.

Terms with respect to which the confirmatory memoranda of the parties agree or that are otherwise set forth in a record intended by the parties as a final expression of their agreement with respect to such terms as are included therein may not be contradicted by evidence of any prior agreement or of a contemporaneous oral agreement but may be explained or supplemented by:

(a) Course of performance, course of dealing, or usage of trade (section 490:1-303); and

(b) Evidence of consistent additional terms unless the court finds the record to have been intended also as a complete and exclusive statement of the terms of the agreement.