Is there any correlation between egt's and coolant temp?

Not really. Albeit when the exhaust temps get hotter the coolant will also get hotter if you push it for extended periods of time simply because the whole engine is working harder. Your EGTs can go from 1100 degrees to 500 dgrees in less than a minute and note this goes the other way too! With a chip or programmer, you could destroy your turbo and the water temps would read absolutely normal. If you are asking "can I keep an eye on my EGTs by watching the water temp" the answer is no.