The amount of hops to dry hop varies by style of course but some general, oversimplified guidelines are 1/2 oz to 1 oz (15-30g) for bitters and British IPAs; 1-2 oz for American Pale Ales; 2 - 4 oz (or up to infinity) for American IPAs. This is assuming a 5USG/19L batch. So to make your kit an American IPA, your 100g of cascade is not unreasonable. I make an all-Cascade IPA with 3 oz/90g in the dryhop. It gives a "bright" citrus aroma, like peeling a grapefruit.