Lynn:

1. Do you have an opinion on the benefits of using radium sparkplugs on a TSIO-550 engine.
 
They work fine. We have seen better advantages to the fine-wires on NA engines, though. We've gone back to massive plugs for TC'd engines. There may be heat-range issues that favor the massives for the TC'd engines.

2. I was doing a lean mag check ( while airborne ) the other day. When selecting the right mag the EGT went up enough to activate the caution light on the TIT. When selecting the left wag the EGT only went up a few degrees.
 
That is completely normal for an in-flight Ignition check.

Walter