I just replaced t-stats on my engines and I noticed that there was a hole (looked like it was drilled) on the "plate" part of the t-stat, there is no hole on the new ones that I bought.
I have heard of drilling holes in t-stats before but I am not sure of the purpose or in I need to drill my new ones?

It allows for some flow even before the t- stat opens. Not a bad Idea esp. if you make alot of short runs.

also helps get rid of steam pockets if youve had overheating problems in the past

As Wally said steam pockects . I had replaced one of mine and did not notice hole I had eratic temp all the time until I figured that out.

Well, sounds like I have a few holes to drill

Thanks guys

Just hold on tight and go slowly. Those edges are really sharp and if that bit grabs you could be hurting.