C6 hp ranges from 430 (base) to 638 (ZR1). I know the trannies have different gear ratios (manual), but are the other components the same ....like bearings, differential, etc? I'm considering an Edelbrock supercharger for my 2011 GS and am concerned about durability.

 

you getting a M6 or A6?

 

I agreed with your concerned, most people look to increase their power and don't think about the expenses after the power, you're about one of the first I realised is thinking ahead before leaping.
I can tell you from my experience about not thinking ahead and what need to be done to avoid what I had to go through.

Clutch need to change, don't buy a spec clutch because it grabs too much and that cause brakage, but you will need to buy a new clutch, recomends a ZR1 dual clutch by Ligenfelter, smooth pedal like factory.

Transmission and rear is good to change to avoid breakdown time and damages under big hp,I recomend a C6 Z06 2008 and up transmission because its a T6060which is an improvement to the older years, the transmission in not much stronger but it has a larger output shalf which helps with less flex under high hp, now rear is any C6 Z06 rear, only a C6 Z06 rear can work because the larger output shalf restrict you from using a stock rear and its also larger and stronger, they are all 3.42 ratio and there are no gears advailable for them as yet (I do have a set of 3.73 complete rear for sale for the C6Z06) and the recomended application.
Change the axles to the 1997-04 axles, they are stronger and better, the new ones break very easy with more hp than 30% over factory.

Remember the old parts can always sell to recover some of the expenses it cost to improve it.
You will also need to get a QTP bellhousing, as a MN6 its your safety to change that because you will not like to shatter a clutch at high RPM and loose your leg. The QTP is steel and the OEM is alluminium, remember safety to yourself first.
Now after supercharging your baby you will be ready for what ever has to come its way, you could get a set of Coilovers and you will need a set of Nitto 345 30 19 sticky tires to help put the power to the ground.:

 

I would think that it depends what you are going to do with the car. Callaway and LPE do not do anything to the drivetrain for their TVS2300 package, so I did not do anything to mine. There are a lot of blown Vettes with stock drivetrains. For Callaway, the GM 5 year powertrain warranty still applies so they certainly are not expecting any failures.
If you are going to drive it hard, then yes, you better look at upgrades. But, why not wait for a failure, unless you have money to burn?
Larry

 

Some people see it differently, I for sure saw it different, My advice was to upgraded the parts before breaking it and sell the take out parts for a reasonable price to help off set the new parts price, so now that is not having money to burn, and besides it never had to break down on the road to cost an additional towing cost, so its a win win situation.
A wise man should know what he is about to do and decide which way is the best way for him, yes I agreed not much people can really buy a car, then do upgrdes to the drivetrain and still add additional power around the same time, its expensive to handle a big load like that the same time but its the best way to do it.

 

If you're going to be making 550-650rwhp all you need to worry about is a new clutch....this is for street driving.

If you take it much to the quarter mile track, and are looking for great 60's with a sticky tire, then up grade your half shafts and possibly a dte brace.

Save the rest of the money Trinic5 has you spending for down the road with the motor breaks, ie cracked piston etc...

 

The OP asked an opinion as to what drivetrain parts should be upgraded , well this is my opinion and its like building a house, the stronger the foundation the bigger you can build the house but you can also do the strong foundation and put a small house just to live for a while.
Believe me, the way I am advicing him, it wouldn't cost alot because all the new "used parts" can sell for a very reasonable price to offset the new parts price and at the end all the upgrades will cost 1/2 the amount than if he decide to wait until it breaks and have to replace it one by one, hence the reason most cars with big power are always in the shop.
The only thing about my way is yes you will have to come out with a few dollars up front, the labor will be cut tremendously because it will be a one time labor price, downtime is only one time and remember life is short, so therefore time is more important than money.

I did everything as I mentioned above so I should be able to handle the power I eventually ended up with presently 860rwhp/810lbs with my new forged LS3 motor
I even repainted my car when it was new(1000 miles) and added the wide body (ZR1 body parts) and did my complete interior and some carbon fibre inside and outside parts.