Hi Marcus,
Many years ago we (Aaron and I) built a Magnum from plans. We had a triple cored wing and used sheet stock for all the control surfaces. It flew really well , but two things happened. One, the finish went South very quickly, and Two, we had just stared using tuned pipes and out Magnum was not set up for a pipe. It has been waiting on a new finish for many years. I hope to get it redone once I get the projects now underway completed. Not sure what engine I will use, I have ST G.51s that run great plus an OS .45FSR and an Evo .60. Either way, I hope to get it finished and finally put a number of flights on it. As it sits, it has maybe 2 dozen flights.
Keep on going with yours!
Bill