350cc & 450cc, pectoralis muscles too tight, could we revise the size of smaller implants? (Photos)

I would suggest going smaller since these look quite large on you. Plus, smaller implants will settle down easier into place and not stretch the muscle quite as much.

if the muscle is too tight for placement of the implants then it might be a good option to place them over the muscle. I prefer subfascial for this. If you had dual plane under muscle, then the muscle should be re-attached where it was cut. Fine-tuning the implant size for better symmetry might be easier with over muscle/subfascial, but there may be other things to consider.

Based on your pictures it does appear you have a size asymmetry. This is something that can easily be resolved. I have been in practice for over25 years and augmented thousands of breasts. I have not encountered a pec muscle to tight. I have seen many pts who have had implants way to large for their dimensions for revisional surgery. I would talk with your PS as after 6 months the pec muscle will have expanded. I hope this helps.