Depending on the air intake someone can hear when the car changes from the long runners to the short runners around 5,500 or 6,000 rpms depending on the tune. If the DSI clip is broken it should be in the short runners all the time, so the car would not have the low end power it normally does.
If the DSI clip is broken sometimes you might hear a noise coming from the DSI module trying to switch the runners.
There is a long cable to connects up to the right side of the intake manifold to the dsi clip. It can be seen with an aftermarket air intake. You probably would need to remove the stock air box out of the way to sell it.