1400 degree EGTs seems to be the norm and a shot of meth brings her down to 1200 degrees

why?

I am working on figuring what RPM my exhaust timing and header lengths are tuned to and sizing my tail pipe diameter.

I don't know how much cooling of the exhaust gases takes place throughout the system.

I don't know if you can use automotive guidelines because of the potential for cooler exhaust gases.

It seems from the replies above that that the water jacket has little impact; but I would like to measure at the collector to be sure.

I've build a wedge/spacer installed between the collector of my EMIs and my tail pipes which I've installed my egt probes. I have 4 SS Competition sytems installed, one in each bank.

I can't tell you any results on the motors yet as they sit on the shop floor ready to drop in at this time. (waiting on flood waters to drop so I can get my boat out)

Is your wedge/spacer like a nitrous plate? but with the EGT bung?

That sounds great. Good luck with the flood, watch out for debris.
http://www.google.com/search?q=house+floating+off+japan

Any advice on brand, installation, lessons learned is greatly appreciated.

Lessons that I have learned from EGT's. I will only use EGT's as a reference tool and only with a tune from an AFR. You can run an EGT and see temps from 1200*F - 1400*F depending on the placement of probe from the piston. (my experience I have the pistons to prove it ) And this is on the same tune. If I do not have an AFR I just run it a little fat.
Innovate LM1 or LM2

Like a nitrous plate I made to angle the risers down to match the transom holes. I drilled and tapped them for the probes. I could email you a pic.

I have an Innovate AFR but no place to mount the sensor. My spacers are only 1/2" thick. I use it on bikes on the dyno and shove it up the tail pipe. No water in them tho... I'd like to figure it out for setting up jetting.

I really need to do a set up like this for my lightnings, where can I get a probe in on those for EGT's ? thanks Rob