You might consider putting on flying wires. The one that crashed on it's maiden flight at the field and the unbuilt kit I traded off, had weak light balsa for the horizontal stab. Once the back end folded, there wasn't much hope. The pilot had just pulled out of a shallow dive when the stab snapped and it continued straight in.
I've got both, the ST 45 and Mag. 52 with the ST having more power, but the 52 more steady torque. You won't gain more speed with the Magnum.