I use Evans NPG-R which runs a little hotter than conventional coolant but has a boiling point of 400F @ 7psi so it isn't prone to localized boiling spots.

Back when I was NA in the 90-100F summer heat in prolonged stop and go traffic I'd see temps up to 214F but never above that. Normal cruising was around 185-205F. Note this is also with BHR radiator as well as Mazmart water pump and thermostat.

After the turbo with MM tune with the lower fan turn on speed I haven't seen temps on the street above 200 though I still don't have a lot of data yet. According to MM it was sitting around 214F on the dyno. Even when really getting on it the few times I've been out the temps have still held constant at 185-190F. Maybe I can actually get out to the track this Spring for some strenuous tests.

 

let me see some pics of you're gauges.

 

Here is a shot of mine in an extreme temp situation (accident on I-35 when its over 100F).

http://www.flickr.com/photos/9krpmrx8/4913068007/http://www.flickr.com/photos/9krpmrx8/4913068007/ by http://www.flickr.com/people/9krpmrx8/, on Flickr

Here it is at a more reasonable temp

http://www.flickr.com/photos/9krpmrx8/4896788462/http://www.flickr.com/photos/9krpmrx8/4896788462/ by http://www.flickr.com/people/9krpmrx8/, on Flickr

Oh, and cut the **** with Celcius