I've still yet to hear an explanation for Tren cough that I've found personally compelling. I've used AAS for over 20 years, in fact my first ever experience with any compound was with Tren Acetate in the form of finaplix pellets. I was too young, and a bit scared of needles back then, so I did a method I found on one of the old discussion forums; ground up the pellets, mixed them with microwave warmed DMSO gel, applied it to the tops of my feet, wrapped them in saran wrap and then an ace bandage, and slept with it on my foot overnight. It seems so ridiculous looking back on it, but it did work pretty darn well from what I recall, other than smelling like garlic the whole time, and tasting garlic every night.
Anyhow, fast forward some and I was doing the home brew injectable route with Finaplix, and sometimes component TH, and had smartened up a bit by added in testosterone to my "cycles". The Tren cough was something I was very familiar with. It literally felt like Russian roulette with every injection. Due to having nearly unlimited access to it, and being young and stupid, I did some insane things with Tren. While I won't go into too much detail as it's a bit embarrassing, on more than one occasion I would take over 1g of Tren in one sitting(4 syringes full of 3.5ml of 75mg/ml Tren), and several grams a week for periods of time throughout my 20's. When people brag about high dose use, I typically cringe a little, so understand this is not an attempt to brag because all it shows is that I'm stupid and since I never became a pro, it's even more pathetic. It's like "you took all that and still look mediocre?".
I'm getting to my point. I've used Tren for a long time, and here's my experience with the cough. I've never had the cough from any other compound, regardless of carrier oil. When I'm taking Tren, I've usually used Acetate, and typically inject EOD or ED. My cough frequency is anywhere between 10-20% of injections with Tren in the syringe. The percentage of Tren in the syringe vs other compounds doesn't seem to matter. A period of time sticks out to me in particular where I was injecting Tren every day, and would get the cough an average of somewhere between 1 to 2 times a week. This went on for quite some time, maybe 2 months, before I switched to an entirely new source for my Tren. This was a source that brews relatively light, very optically clear, Tren. After switching, I never coughed again. Ever. I know Tren, and this was definitely the real deal and was giving me what I expected of it, save for the cough. I've since continued this sources Tren, as well as an additional sources Tren that is also new to me, for maybe 100 or more injections, and still, I have yet to get so much as a tickle in my throat from either. I know this is anecdotal, but for me personally, it's undeniable that there has got to be something about this Tren in how it was brewed that makes it lack a certain something that was triggering the cough for me. I'm exceptionally curious as to what it could be. Stepping back, I'd totally understand people saying my two new sources are fake, but they're both highly respected sources here.