Swain has good reviews.. I don't know of any users personally, but I did have a buddy who used Techline Thermal coating on his Turbo Volvo(a 2.3 inline 4) and the temp differences were amazing. He coated the combustion chambers, valve faces, piston tops, and then used a different caoting on the inside of his Exuast manifold and turbine housing , and then their high temp 2000+ black on the exterior, and WOW... Before when the engine would heat up to opeating temps, you would have to wait about 4 hours for it to cool back to ambient(turbo housing, etc...) but with the cating it was back to ambient in under 2 hours...To me, if you are tweaking an engine, this alone is reason enough to coat things,but also when you think about things thermally, if the engine parts are not absorbing as much heat from combustion, then the excess temps that would normally be abosorbed bt the head, tubo, exhasut manifold, etc... are being evacuated with the now hotter exhaust gasses, thus an increase in exhasut velocity(hotter gasses fow faster than cooloer ones), allowing a larger diameter pipe to be used with out as much flow decreases. Also , longer life on the water pump and the turbo's center core.. alot of good reason's to use engine coatings...
Good luck
