If you
need a 4 stroke, the Saito is a performer and if you lube the bearing with afterrun, it will last forever. If you still want performance and want to save some money, an OS 160 would be the better choice over the Magnum, especially if you get the Ultimate.
Wait!, if you get the Ultimate, put a DL50 on it! $390 and your'e good to go for power and it won't be too heavy for that plane. Ask anyone who has had a 25-27% Ultimate with a DA50 and it is a blast.
Head spinning yet?