If they don't sell one, I'd recommend Union's Curable Reducer/Detackifier. There's really no reason why you can't use different manufacturer's stuff with any particular plastisol, since all plastisols are basically the same. It can reduce opacity, and may reduce a lo-bleed ink's lo-bleed capability. You also don't use a lot of it . . . somewhere around 5-10% max. Go to Union's website (unionink.com) and look it up.
One Stroke Inks has a liquid reducer, although not a "cureable reducer", if you use just a little as directed, you can reduce your ink without affecting the opacity, and the ink still gets cured properly.
Which curable reducer is best? 
