Getting "stronger" is fairly easy. Muscle Augmentation (p. 305 EP) applies a quick bonus to the strength of a morph for a decent cost, completely sculpting and restructuring muscle fibers for better strength and fitness. Being more flexible is tougher. While some morphs (such as the Bouncer) are inherently cultivated for great flexibility (Modeled via the Limber trait (p. 146 EP)) this option is very resource intensive, requiring specific cultivation of a morph from it's inception to generate the desired genetic traits. For those who wish to rapidly improve flexibility and fine joint control, there are other options.
Joint Augmentation: The morph's joints have been comprehensively modded to have more elastic cartilage and stronger joint fibers - allowing more inherent flexibility and control over minute adjustments at points of articulation. Apply a +5 modifier to COO. Also adds a +10 to any test where flexibility would help - this bonus does not stack with the Limber trait. [High]
Despite it's simplicity, Joint Augmentation is actually fairly rare. While it is known or suspected to be used by several high-profile escape artists, it generally does not get wide use. It's primary market is actually to help those with joint damage or degradation, due to aging or a hard lifestyle. While Healing Vats can repair most damage and alleviate symptoms, damage can still persist - for those who still require frequent use of their joints in a singular biomorph, or are against resleeving or healing vats, it is a common therapeutic proceedure done over longer courses of gene therapy. On the less savory side, many mercs and assassins utilize Joint Augmentation on top of natural morph aptitudes to grant additional flexibility and emphasis the "hand" part of hand-eye-coordination.