Either will do, I would have thought they're not mm perfect and you would never notice the difference between a set claiming to be 35mm and a set claiming to be 40mm.
Not 100% sure though!
Mine are Pi springs, can't actually remember whether they are 35 or 40mm tbh. With 17's on 205-40R17. If you look up Pi springs I'm sure they'd only sell one size.
17's and 35-400m lowering is just perfect on the Bravo! The wheels fill the arches spot-on, and there's no scraping, even with a full car. The Mrs hates the ride though, but I think it's an acceptable bumpyness for how good it looks!!