I just got a Gates from the local independent auto store. I has a huge opening available and has a rubber seal just like the Cummins I took out (with the seal tangled up in the opening). It is a 180 and the needle stays exactly on the 'about 180' mark.

 

I tried the 180 for fuel efficiency. It RUINED my efficiency. Absolutely MASSACRED it. I was told it would, but no one had any real numbers, and being a skeptic, I thought it was a cheap experiment. I went from 17-19mpg current mods minus chip, hand calced tanks to 14 just with the stat changed.

+1 to the puny Napa stat. I don't have too much trouble with temps with it, but it IS puny alongside the factory one. Plus the factory ones often (always?) fail open. The Napa will fail closed. But usually folks notice more fluctuation with the factory stat.