yesterday I had some time to kill so, I decided I'd go ahead and put the 180 T-stat in, no problems at first, Today I turn my car on (sat for about 3 hours) and the meter jumps up to 200 in no time at all, whats the problem? oh, I haven't added any water to the anti-freez yet either, just pure anti-freez as of right now.

i put my 180 degree stat in to and it done the same thing the first time I ran it for like an hour... Now it doesn't do it.

Pure antifreeze doesn't dissipate the heat as quickly through the rad as the proper mixture (which is 50/50). It is very important to mix this because it is the way this cooling medium was designed both for the cooling aspect as well as the anti-freeze aspect. Just one note....you didn't put the thermostat in upside down did you?

oh, what does your temp usually run now?

don't think I did, pointy edge is the top right?

Mine runs at about 180-190. I have seen it go up to about 195 in stop and go. With the 195 stat it would run at about 200-205 (still not bad for it though)

After installation did you run the car to build pressure, shut off and bleed the air
from the bleeder screw on the thermostat housing?

Alot of good advice here. Check it all.

Proper 50/50 mixture, and topped off.
Air bled from the system.
Thermostat properly installed and verified that it'* working properly.