Right, I was just pointing out that the potential issues you cited I think could be easily solved. I.E. a 6 bolt 4g63 from the factory that was dirty or had a bad batch of bearings would quickly fail. But that same 4g that was properly cleaned and had good bearing can easily hold double it's factory power output because of it's actual design.
Now if the fundamental design of whatever 4cyl used in the Stinger/G70 sucks, then yeah, it would be pointless to ever try to make more power with it.