Time limit for customs inquiries set with possible extension; excludes periods of judicial stay and overseas information requests. Statute imposes a time bar requiring that any inquiry or investigation under the Customs Act that leads to issuance of a notice under section 28(1) or 28(4) be completed by issuing such notice within two years of initiation of the audit, search, seizure or summons, subject to a single recorded extension by the Principal Commissioner or Commissioner for sufficient cause; periods of judicial stay and time spent obtaining overseas information are excluded, and the provision does not apply to proceedings already initiated before assent.