Glowing manifold branch

One thing after another! 
Finally got my caddy started and was running for about 30 minutes and I noticed the third from left manifold was glowing red the others weren't ? Any ideas what this could be ? It has recently had an exhaust put on and the timing was all out and now has been set, it does take an age to start which has never been a problem previously but not sure if the garage that did the exhaust mucked about with anything? I had it purring previously and no issues with the manifold before 

Thanks in advance 

any developments on this?

Just a thought..... blocked or partly blocked exhaust manifold from cylinder 3?

Hi mark think it may have been the mixture as when I had the mot my emissions were at 0,17 I've adjusted the mixture and it seems to be better, also it was running lumpy and taking an age to start so maybe the timing so checked that but was ok, it glowed  yesterday for about 2 minutes then stopped and was idling for about 30 minutes and wasn't that hot at all,  just the brake imbalance to cure and apparently I have to have side indicators on my year of caddy so need put them on them ready to re test we are getting there lol 
Thanks for the help 

2% is what you want to aim for.

You need to adjust the timing to what fuel you are using super unleaded or normal unleaded, best to run on super unleaded then you set it up by the book, normal unleaded to need to retard the timing.