Found Hyundai stock audio add Direct Aux-in
This is most difficult brand for direct aux-in. Namely,
HMP380 (MP3 Capable)
H910, 930, 935, 940, 941, 950 ( these maybe Asian model number equivalent to H260-295 series)
These models all have CD changer ports. And audio are decent of quality.
No US Adaptors from any (Cruchfield, Ice-link etc.).
Found a company can make it and tested fine. Direct link to CD port. Sound beautiful without noise. Price nice: $29.99 plus shipping.
But mini order 500 pc . I just don't know if that many people will be interested. Seem to me very small demand.