Im 5'8" and 160lbs and currently a b cup. Is 525cc implants to big or will it give me a nice d cup?

Your height, weight, and starting cup size are helpful, but not enough information to decide what type of augmentation to expect with a 525 cc implant.  Volume (525 cc) is less valuable data than dimensions (width and projection) in my opinion.  525 cc could be a very wide flat implant for a broad chested woman who wants small augmentation.  525  cc could also be narrow implant with "ultra-high" or "full" profile that would add two or more cup sizes for thin woman with narrow shoulders and chest.  Find a good plastic surgeon, listen to recommendations and reasons for recommendations, try sizes and styles on in office (and/or computer simulation), then make your best decision.  Size is only one component of many that contribute to a quality result.  Others are shape, symmetry, texture, scars, preservation of sensation, avoiding implant visibility, and more.

  I think the best advice I can give is to try on sizers in a plastic surgeon's office to help determine what size you would like.  Cup size varies so much manufacturer to manufacturer and there is not a standard.Kenneth Hughes, MDLos Angeles, CA