A company is evaluating a project that requires an initial investment of ₹800 lakhs and is expected to generate the following cash inflows:

Year	Cash Flow (₹ in lakhs)
1	180
2	200
3	220
4	240
5	260
6	280

The project has a discount rate of 18%. Depreciation is applied on a straight-line basis over the project's life, and the salvage value is ₹50 lakhs.

Required:

1. Calculate the NPV of the project.
2. Determine the IRR.
3. Compute the Payback Period.
4. Assess the impact of a 10% decrease in initial investment on the project's NPV and IRR.