Never had a magnum but I have to agree that they are poor engines because... As one of our members at the flying field who has one said "oh don't let any one else tell you otherwise, they are a peace of sh*t(sorry thats what he said), but they are a lot cheaper then OS or Satio and I guess you get what you pay for". I think for the most part "you get what you pay for" is right on the dot. Oh yeah he had fuel leaking out of his header= lost of compression but it still run though.