Provia 100 and 400 are both lower contrast films than Fuji's staple shockers, Velvia 50 and 100, implying that you can push/pull Provia with excellent results, but "fit the film to the task". Use Provia 100 in bright daylight with strong shadows, then compare the same thing with Velvia 50/100. Provia can benefit from occasional POL use to intensify a rather muted palette (compared to Velvia's much loved "Disneycolour") but if you need to gain contrast, you're better off just switching films i.e. Velvia for diffiuse to hazy conditions; Provia for point-light, contrasty or long exposures.