Individual EGT's would be cool to see a lean cylinder (ind WB will do the same thing) but since timing drops EGT alot of people throw timing at it and then fail to realise that the increase in detonation potential is far more likely and costly.

EGT also rises further away from the head depending on timing (how much is burning outside the combustion chamber) so a 1650 runner temp does not correlate to a 1650 head temp, correct?

 

Exactly, runner temp does not (repeat NOT) correlate to cylinder temp.

See the problem with EGT's has to do with ignorance. Import boyz saw V8 guys using them and tried using single probe units. It worked, when EGT's rose you knew you were off tune. People usually thought it was too lean so they would add fuel via an AFC. Specifically speaking on DSM's people would add fuel (IE airflow) and the car would reduce timing and the EGT's would come back down. The reason EGT's went high to begin with is because the ecu was pulling timing due to knock. It was a whole dog chasing his tail ordeal.

The reason KNOWLEDGABLE V8 guys use EGT probes is to measure fuel distribution across all 8 cylinders to spot out leaning out issues (yes EGT's will change a bit with AFR variations). Fueling issues across all 8 cylinders is much more of an issue on v8's.

Now today things are great. You can set up your car to datalog across all 4 cylinders with economical widebands. You don't have to spend thousands anymore to do this. You don't have to run EGT's to save a few bucks and then interpret these values as fueling issues. We really do get a lot of great stuff for cheap these days!

EDIT:

Really smart V8 guys on a budget kill the motor on the top end and coast to the return lane and then pull out the plugs and put them on an index block to read back in the pits. Put 8 new plugs in and drive her back to the pits. Walla reading fuel distribution issues for $1.79 a plug

 

Do they even have WB O2 sensors that can withstand the exhaust temps at the runners for more than a handful of pulls?

 

Well the prime reason i did 4 egts on my manifold is more to monitor the engines Health. If all 4 cyc are equal in temps then you know your good. The WB and knock sensors help me with tuning.

And the biggest mistake alot of people make also with EGT probes is not replacing them overtime.

Off the top of my head to jacks question: the Wide band would prob restrict the flow of hot gasses in the runners...they are not as wide as the O2 housing. Restriction at that small point would slow the gasses down enough to make that bank hotter. As we all know we want hotter faster moving gasses to be hitting the turbine.

 

Yes:
http://www.innovatemotorsports.com/resources/pedigo.php

The normal person really doesen't need to do this. This is the kind of stuff that nascar engine builders do etc.... The average 4 cylinder really doesen't have bad distribution issues. If you are on a stock intake manifold you are usually in good shape (with a quality set of injectors). For someone like you and I you can learn a lot by just buying a fresh set of plugs, finding your favorite straightaway, and doing a 4th gear pull and killing it at redline. Pull the plugs and put them in a piece of cardboard that is marked with each cylinder. Put in your other set of plugs and take it back home to study. Be sure to be liberal with the antisieze and just be gentle when putting plugs back in a hot cylinder head. Also dispite many myths you WILL NOT hurt your turbo killing it hot.