Some 5.3L questions

[bennylava]

Here are my 5.3L questions that I'm hoping someone who knows that engine very well can answer.

1. How much power can you make without affecting MPG (much)?

2. Any estimate on what kind of fuel mileage you'd get with 550hp?

3. What kind of longevity can be expected out if those are your power numbers? Will that engine make it past 100k miles if properly maintained? 200k miles?

4. Are the factory heads any good for making power?

5. Is it easy (enough) to get to 500+ hp while still being naturally aspirated? Or is this where everyone adds a turbo? I want to stay NA.

6. Is it difficult to find a Gen3 junkyard 5.3L?

7. Is the best test of a Junkyard 5.3L to pop the valve covers and look for sludge?

8. What kind of power can you make staying naturally aspirated, and keeping the stock heads? With better headers, upgraded roller rockers, good exhaust system, etc. How much can you squeeze out of it?

Thank you!