All transistor boxes do. Any transistorized ignition box has a slew rate of 1 to 1.4 per 1000 rpm.
Until you get away from 1960s/70s technology and step into computer controlled ignition your timing will retard as rpm & loads build.
I have seen on a timing light myself that the LX101 Standard ignition box does not retard timing. Now, having said that, "I GUESS" I could have had a defective one. I have heard other people say the same of the Standard box, though. So I don't know. I do know that the orange box does retard timing just as described and know why. The design is an intentional one to keep detonation down at high RPM.
