Can 455 cc moderate plus provide you with as much projection as a 400 cc high profile since the moderate is a bigger implant?

You need a formal evaluation by a licensed plastic surgeon and expert in breast augmentations to determine what is best for you and your goals.Proper breast enlargement is not a "cookie-cutter" procedure where the same technique is applied to every patient. Every woman who comes to my practice has unique needs and different goals for her breast augmentation. As a board-certified plastic surgeon, I always listen carefully to each woman's concerns and thoroughly discuss the key points of the procedure. I also take into account their overall height and weight, the size and shape of the underlying chest and ribcage, the tightness and elasticity of the skin, and the amount of natural breast tissue. Prior to the procedure, we discuss and make decisions regarding location of the incision, whether to place the implant under or over the chest muscle, and what type of implant to use (I offer multiple types of silicone gel breast implants, as well as saline implants).
My experience performing thousands of aesthetic breast surgeries in a wide anatomical range of patients enables me to achieve consistently beautiful and natural results that are customized to each patient’s body type and goals. These results are the product of extensive communication, meticulous planning, and skillfully executed surgery.
I suggest consulting with a board-certified plastic surgeon and expert in Breast Augmentation surgeries. - Dr. Cohen

This depends on the brand we're referring to. Different brands have different projections. Your Doctor who has suggested this implant to you, will be able to explain how the implants will project.

Hello, technically a large moderate profile implant could provide as much or more projection than a smaller high profile implant.  Your surgeon can readily determine the projection of each implant for you based on their catalog (the exact brand is required to do this).  Depending on a person's breast dimensions and other factors, sometimes a moderate profile implant is a good option even for patients who are seeking more fullness and projection.  This is an excellent topic to discuss with your surgeon since they will know important information like your breast width, tissue thickness and skin tone.