I've been monitoring mine with spongerider's techtom. We fluched the radiator when we were doing 60k. It's been running 178-181 constantly with ac on too. In traffic the highest I've seen so far is like 189-190. Is that Nismo radiator pretty big compared to the stock rad?
: When crusing at 70mph in ~100 degree heat, mine stays steady at 179-183 degrees (even with the a/c on). The only time my TT gets past 200 is sitting in traffic with the a/c on. Are you using Water Wetter? Maybe my Nismo radiator is good for something afterall! :-)