Blanket on my T3 turbo dropped the temp 3 inches away from 500+ F, to barely above 95 F. This dropped underhood temps by several hundred degrees and kep the radiator cool as well (T3 turbo SE-R).
Now, how good goodspeed heat management properties are, that's another question. And for something which requires quiet a bit of research and cost to get the material grade and makeup correct, I would be a little skeptical of a knock off.......but if it works, it works, I guess
I use either Thermotec or DEI materials when it calls for it.