I posted this in another thread on cyberlimbs, but to repeat in breif:
Cyberlimbs do not raise your attributes, they have their own attributes. These attributes are used in place of your normal attributes for certain checks. Pg 455-456 of SR5 has details. Cyberlimb attributes are not use in to calculate things such as limits (and a few other things). In those cases, use your normal stats. So if you dump strength to 1 but have an arm with strength nine, you only get to use that strength 9 for things involving that arm only (punching someone, holding something with your cyberhand, etc). You can run your agility and strength for the limb up as far as you want provided you are following the rules for cyberlimb customization and cyberlimb enhancement on pg 456.
Things such as muscle replacement, muscle toner, etc, DO directly raise your attributes. They are used for all checks and calculations, except for knowledge skills and contacts. (if you had augmentation that affected logic or charisma). This is where the 4 point rule comes in. If you have a 1 agility you can raise it to at most 5 with these type of augmentations.