Does this place breed troll, or just draw them? It's amazing how even the most laid back thread topic can devolve into a flame war.
But what the hell, I'm bored, so I might as well chime in. lol
On the R/T, not too much, I have an electric fan on hand, waiting for a fan controller so I can dump the clutch fan (for more MPG). After that, I'm toying with the idea of a belly pan, either from sheet aluminum from Lowes, or from pre-made C/F sheets a buddy of mine can get from the fab shop where he works.
Right now, since it's my daily driver, I'm focusing on MPG. Lowering drag on the body and removing drag from the engine (fan) should both go a long way toward helping that goal (one at lower speeds and acceleration, the other at higher speeds and cruising).
Next will be either a new diff with steeper gears (lower revs at speed), or possibly new rims, since I can get the R/T rims in 20" (vs the 17"s on there now) and keep the same profile tire, thus killing the wheel well gap and increasing rolling diameter (lowering final drive, and revs at speed).
Eventually, I do plan to replace the craptastic log-style exhaust manifolds for headers (probably have to custom build them), and also more work on the CAI, as well as intake manifold.
On the WS6, I'm saving for a new lid (good for 5rwhp, as proven on the dyno and drag strip), HP Tuners so I can tweak a little more out of the LS1, and parts for a CarPC (replacing the headunit and amp with a screen in the headunit's location, and a PC in the back hooked up to the sound system with a new amp).
After that, maybe some appearance mods, or maybe a set of sways. 'Course I sill need some good rims too, but I haven't yet decided exactly what I want, nevermind the cost. I need something though, I'm seeing more and more black LS1 WS6's around my area and it's starting to piss me off. lol For the longest time I was the only one, but now I have to find some other way to stand out again.
Kinda-sorta considering exhaust too. Mac-Mids are definitely in the mix, as well as a possible electric cutout, but I'm toying with a cat-back too. Trouble is, I like the stock sound, it's just a touch on the quiet side at times. (so I think the cutout might be the ideal mix. I've heard a WS6 running open headers on youtube and I don't know about the volume, but the sound was sublime

)