LT1 bolt ons

[Templeton Peck]

I'm close to finally buying my first Vette and I'm pretty sure it's going to either be a LT4 or LT1 C4. My question is regarding the LT1s and simple bolt on performance upgrades. I don't plan on doing a whole lot, probably a new exhaust and intake.

What kind of performance gains could I expect from a LT1 C4 with those upgrades?

Bonus question: How much more maintenance, cost etc. should be expected on a manual vs. automatic?

Thanks.