i'm powering with an OS 160 twin...........played with the 1.20 surpass, but after reading all the reviews, decided it would be marginal power.
i know the Saito 1.50 would be great for this bird, but after running the 1.20 (single) and the 1.60 twin, decided i like the smoothness of the twin.
bought a couple of the Keleo exhausts for the twins. nice pieces for the price.