The Magnum 52 is a very, very powerful engine. They had two problems that they may have fixed by now ..... I hope. The first was the carb; it had a very fat mid range which can lead to a lot of dead sticks at part throttle. You need to try it with your prop/pipe combo to find out. If it has this problem it can be easily fixed by reshaping the point on the low speed screw. Search in this thread for info, post # 233.
http://www.rcuniverse.com/forum/m_29...reshape/tm.htm The other problem was crankshaft failure on SOME engines when pushed hard i.e. tuned pipe & speed prop. This engine has a huge crank port = thin wall+power+run time= snap! If it happens, it happens.
On a speed plane (clean), a good starting point prop for this engine with Ultra thrust, Jett or tuned pipe running 15% would be an APC 9X9 and I would expect well over 16,000 rpm on the ground.
Good luck.