The Magnums are better at certain things... they flow fast, but not record numbers... On getting 270 from a set of Xs with home porting, the bench wasnt right or he's tellign stories. Not without welding or epoxying can that be done. Magnums are a very good mild to medium performance head, expecially in the EQ versions that take LA manifolding and do not have cracking issues. The issue comes tryign to get bigger cams into a magnum headed engine. They get expensive to put a real cam in. So it becomes cheaper to use the LA version aftermarket aluminums and port as needed.