My Jabiru 3300 has about 540 hours on it. Its second annual inspection revealed very low compression on the number 5 cylinder. The exhaust valve was burned. The valve seat was OK. The new valve cost about $50 with gaskets and o-rings. All parts were in stock at Jabiru Pacific. Jim over-nighted the parts to me. The repair was easy and the plane is back in the air. Today it flew 635 miles and runs well again.
One worry; the engine has slowly been increasing its oil consumption. It burns about a quart every 500 miles.
My Iridium spark plugs have 200 hours on them now and the gap has not changed. I recommend them.