I have the 2013 2SS RS auto with the LS3 and I am trying to keep it a daily driver but I want it at mid to high 600's on RWHP and someone had said you can do this without a supercharger which I would love to do if anyone can guide me in the right direction thank you.
We have done countless cars in the 550-700 rwhp range with o.e. shortblocks and consider them to be reliable packages. This power # is the limit of comfort though with the o.e. short.
Looking over this thread it seems you have a solid budget and realistic goals in mind.
The easiest thing to do is install a Whipple and a set of full tubes this would get you to your goal at or under budget depending on what other things you have in mind.
I always recommend attacking the main floor before adding on top. The bottom end of these are solid so the foundation is stout out of the box(as long as it has been well maintained of course)
Cai, cnc heads, camshaft(don't get fired up chapel!lol) front to back exhaust netting 420-460 rwhp depending on camshaft choice.
Then add the supercharger of choice to complete the package this would put you over the top of your goals power wise.