Follow-up to my earlier post:
I tried the TFV8 again with the X4 coil and just OK at 80 watts, but really hot at 100 and up. I pulled the coil and took a close look under my magnifying glass. There appears to be some cotton blocking the bottom of the coil, not sure if that is normal or not. I didn't compare it to the new X4 I have because I chose to replace it with a T8 coil. While the X4 has 4 air flow holes at the base, the T8 is virtually wide open for what looks like far more air flow. Says it is "best" starting at 120 watts, but that is as high as I have gone so far. Hitting nice, slightly warm. Nothing remotely close to the heat I was getting from the X4 coil. So I am staying with the T8 coils and will keep my new X4 for use only in an emergency.
Before hitting "Post Reply", I cranked it up to 135 watts for a couple hits, then 140 for a few more. Vapable, but a bit warm for my liking. I'll let somebody else give it a go at the 180 top "best" level. Won't be any stealth vaping at 140!