The four-moduli Residue Number System (RNS) sets such as {2 n -1, 2 n , 2 n +1, 2 n+1 -1} have attracted a lot of researches during recent years. However, nowadays applications require higher dynamic range. This study introduces the RNS four-moduli set {2 2n , 2 n -1, 2 n +1, 2 n+1 -1} which is obtained by enhancing the moduli set {2 n -1, 2 n , 2 n +1, 2 n+1 -1}. This enhancement didn't increase the total speed of RNS arithmetic unit since the critical modulo in both of the moduli sets {2 n -1, 2 n , 2 n +1, 2 n+1 -1} and {2 2n , 2 n -1, 2 n +1, 2 n+1 -1} is 2 n +1. Besides, an efficient RNS-tobinary converter for the proposed moduli set is designed using a two-level architecture where a previous converter design for subset {2 2n , 2 n -1, 2 n +1} is used in the first level and then a two-channel Mixed-Radix Conversion (MRC) algorithm is considered to achieve the final result. Comparison with a recently introduced RNS-to-binary converter for a four-moduli set with the same dynamic range show that the proposed design results in higher speed.