I use ECA, but only as a workout stimulant. Not as a fat burner, taken several times ED.
Many say T3 helps nutrient metabolism, but for me I have trouble holding weight (even at 25mcg ED or EOD) when bulking-so youd have to experiment with this yourself to see.
Bottom line though-if your bulking you should actually try to get a little fat IMO! That way you know you are getting all your nutrients plus some. I just keep the sugars low especially at night-beside that high protein/EFAs and anything goes!
Personally, I would avoid any effort to avoid putting on fat. No cardio, no thermogenics. If you notice that you're getting really fat really quick, just drop calories a bit until you're only gaining 1-2 lbs a week. That's a pretty safe protocol. Of course you could just go all out, and gain 5-8 lbs a week, but that would definitely put on some extra fat, assuming you're already in decent shape.
Bottom line-any attempts to stay lean (diet or cardio)
may be comprimising your ability to gain muscle and bulk.
I like Steves idea-if you are getting way fat too quick
cut back on diet a hair.
But also-its all in your goals. If your goals are to gain muscle
at any cost (getting a little heavy) go for it. But if youd like to
stay a bit leaner, it may be acceptable to not gain as much muscle in order to look right always. Up to you!
I also think that knowing your own body comes into to it.
I have reached the point I understand that when I cut down, it takes me a lot longer to reach my target, and I seem to sacrifice more muscle than I would like to.
Therefore I tend to sacrifice something on my bulking cycle to stay that little leaner.
However that said if all out gain is your bag, get the feedbag on, sleep as much as possible and just grow baby.