In this letter, the authors analyze the influence of the degree profile on the performance of an irregular turbo code (TC) using hierarchical EXtrinsic Information Transfer (EXIT) charts. Then, the authors propose an irregular TC concatenated with a post-encoder of unity rate at its output in order to improve the distance properties. Through the example of 3GPP2 interleaving, the gain at low but also at high Signal to Noise Ratios (SNRs) is illustrated.