First I used The CMB evo2 pipe but it doesnt work at all. The engine wont rev at all, it worked on the RS. Now I use Daves pipe at 235mm and good speed and throttling. My is a geared endurance boat (Fsr-v).
I also heard that Novarossi pipe seems to work well.
Like Dave wrote, the 45 EVO its much better than 45 RS. Much better torque and pull bigger prop with shorter pipe length.
Only need some small mods to get as high revs like the RS.