I am thinking that many companies use toxic additives to create such strong scent that they send you out of the chair...I know that mixing DOA can really enhance the scent, but I am worried about inhaling those chemicals! I have tried about 10 FO providers, and I think Candle Cocoon has the strongest scents so far. Flaming Candle and Candle Science are a little hit-and-miss, but good choices. Regarding Save On Scents, I agree with the above poster that the quality has deteriorated and I feel like the FO I loved is often chemical smelling and weird. The Extreme quality can be difficult ti work with; I prefer the Ultra.