My 06 sometimes pukes coolant out the degas cap. It has a kdd stage 1 long block, Kc stage 1, oringed heads and oem gaskets with arp studs, and 175/stock injectors. I used to run an atlas 40 as well. I have tried the atlas 80, but I dont like the extra egts that come with it. I’m going to hook a gauge and see where I’m at pressure wise soon, just trying to gather some thoughts. I run tunes from Wdi, tsd, and Quicktricks. I can run a wdi tow tune, and never have an issue. I tow 20k with not a single problem. At first, I was thinking my fan was not working correctly, so I put my bpd manual 7.3 clutch back on, and the ect stays at 190-200 at all times. Before I could hit 220, and still never puked. If I run my tsd tow, or 1.6mpd, it won’t puke for a good while on a very hot day. The spd will puke sooner, but I have to be running kind of hard. My oem water pump went out a while back, so I replaced it with another motorcraft too. The thermostat was not replaced, but it is a motorcraft as well. The deltas are very good. Usually within 10 degrees towing heavy. I stopped at an Oreillys and bought a cap there. They only had aftermarket caps. It lasted a few days, until my motorcraft caps came in. With the 1.6mpd, it puked after a few months. The highest egt I’ve hit was around 1300, and that was for a very short time. Usually when it starts to bog down, I hit the tow haul, and after the downshift, it cools down to 1000-1100 in a hurry. The coolant level is just below the minimum. The highest ect I’ve hit is 225-230, and the highest eot has been around 230 as well. I’m hoping I’m flash boiling coolant somehow. It also has a coolant filter kit and I have elc coolant as well. Any thoughts? I doubt it’s the head gaskets or heads, but you never know. Other than reading pressure at the degas bottle, what else can I test? I don’t have a way of testing the degas caps. Thanks.