yes, tbh im only talking from first hand experience but do know others that have wrapped headers for years without spray and remained fine but then again some of them were much higher quality than thermotec stuff
If you have just bought a new header then it is definatly not a waste of time takes an hour tops to do the job properly and the benifits definatly out weigh an hour of you time..
not 100% free horsepower but releases more of what you already have for the cost of the wrap and your time