Here's a thread on rx7club with good pictures that may help explain this mess to those that have never seen the inner workings of a rotary. Believe it shows pretty well how easy it would be to spot intake port work with the naked eye, let alone a borescope. And why it would be all but impossible to spot exhaust port work with a lollipop or an external template.
http://www.rx7club.com/showthread.php?t=908708
In this pic two stock ports are compared to the street ported iron. The port work is fairly extensive and would be very easy to spot with the intake manifold off. What you need to look at on the stock irons is the lip that is CNC milled into each port (red arrows). The contrast between that milled portion and the cast portion is impossible to recreate by hand. Modification of that contrast, and the resulting tooled surface of what should be a cast intake runner is a dead give away of intake porting. Again, even if it's mild work, it's painfully easy to spot without the need for measuring devices or engine dis-assembly.
This picture in particular
http://www.rx7club.com/showthread.php?t=908708
In this pic two stock ports are compared to the street ported iron. The port work is fairly extensive and would be very easy to spot with the intake manifold off. What you need to look at on the stock irons is the lip that is CNC milled into each port (red arrows). The contrast between that milled portion and the cast portion is impossible to recreate by hand. Modification of that contrast, and the resulting tooled surface of what should be a cast intake runner is a dead give away of intake porting. Again, even if it's mild work, it's painfully easy to spot without the need for measuring devices or engine dis-assembly.
This picture in particular
