I would say number 3 also when i overheated my motor, I melted #3 coil and the others were fine, seems like that is the most common place to overheat....

 

This may come from a lack of experience as far as reading EGT but if you only want one probe installed for whatever reason why couldn't you just place it in the collector instead of on one cylinder? It wouldn't give you an accurate reading on each cylinder but would give you an overall temp that should still be helpful in determining any engine problems. Unless too much heat is lost by then but it isn't that far from where the exhaust exits the engine. Anyone ever tried this?

 

if you have a tublar manifold then you need to put one in each cylinder to do it correctly, if you have a log manifold then you put it right between cylinder 2 and 3 where it would feed the air into the turbo, you supposed to put it about 2-3 inches from the where the manifold meets the head to get the best readings, if you put it farther away the reading aren't as accurate. and if it is in the collector then you dont' know which cylinder is overheating.