Wave digital filters synthesised from two port adaptors are highly recursive structures and hence for high speed implementations it is essential to reduce the latency of the adaptor. This is directly related to the number of addition levels used. Nonredundant radix-4 arithmetic has already been shown to nearly halve the number of levels compared with an uncoded multiplication with much less hardware overhead than the modified Booth algorithm. In the Letter, nonredundant radix-4 arithmetic is applied to the two-port adaptor. The results compare favourably with previous approaches for most coefficient wordlengths of practical interest.