First of all, I'd like to thank all you regular posters for helping me getting everything straight. I'm the rules lawyer of the group, and I make it a point of pride to understand how everything work. I could manage with D&D 3.5, but SR is...wow. Lots of stuff.
Second, for those that have the time, I'd like to run through some examples, just to make sure I got everything right. By the way, I'm currently reading the 20th Anniversary SR4 Core book, if that matters.
Meet Joe Average. All attributes are a 2. Joe has the backing of a AAA's CEO, so money and availability are not important.
1) Joe wants to be stronger and more agile. He looks for Muscle Replacement cyberware. Sadly, since his attributes are 2, his enhanced maximum is 3, so he can only equip a rating 1 MR. Not satisfied, he moves on. He starts looking at Cyberlimbs
2) Joe looks at standard cyberlimbs. He could get 2 arms at 3/3/3. He could use the arm's capacity to install enhancements, but because he has no cyber-torso, he can only go up to 6/6/6. He could lift a car in theory, but in practice his mundane torso would never support the output his arms are capable of.
3) Joe could splurge more essence for a cybertorso. With an off-the-shelf torso and arms at 3/3/3, he can go crazy with enhancements. With 15 capacity in each arm, he buys 1 point of body, and 7 points of agility and strength for each arm. Now his arms have 4 body, 10 str and 10 agi. But they're full to capacity, so no fancy gadgets or cyber-guns can fit in there.
4) Rather than go for a cyber-torso, Joe could order custom-made arms. Nuyen is burning a hole through his bank account, after all. He'd love to spend millions on these parts, but sadly, humans have a natural maximum attribute of 6, which is where he'll have to stop. He orders both arms with 6/6/6, but without a cybertorso, he can only enhance them to 9/9/9. Still, not bad!
5) Combining all of the above, Joe could get a torso, 2 arms at 6/6/6, and boost them like in scenario 3. He would now be the proud owner of 2 arms with Body 7, Strength 13 and Agility 13. Now watch me juggle those cars!
Did I do anything wrong in the above scenarios?
Thanks a bunch :-)