I went through some trial and error and was never happy with a cherry scent I got. too expensive and too impotent!
I got as far as calling KC chemical with no luck. They take out a big expensive looking ad in car wash magazines advertising 'scent sations' but it is not listed on their website. i gave up.
I've been playing with quest recently and like most of their products. They do make a concentrated scent but it is designed to be injected into the water stream via a dual tip hydrominder eductor. I haven't tried just mixing some in.