SC modulation (Single-Carrier) with FDE (Frequency-Domain Equalization) combined with iterative (turbo) FDE schemes has excellent performance in severely time-dispersive channels, making it a promising candidate for future broadband wireless systems. In fact, it was observed that the performance can be close to the MFB (Matched Filter Bound). In this paper we consider a class of iterative FDE schemes and we study the impact of the number of multipath components and the diversity order on its performance. It is shown that for a high number of separable multipath components the asymptotic performance approaches the MFB, even without diversity. When we have diversity the performance approaches the MFB faster, even when we have just a small number of separable multipath components.