Calculating Reserve Amounts w/ Increasing Rents

[Hunter Peterson]

When calculating cash flow, you hear a lot about how much you should budget for various reserves (7% for vacancy, 10% for property management, 5% for cap ex, etc. etc.). My understanding is that you're calculating a percentage of your rental income. However, this assumes that your rent is fairly steady from month to month. 

Assuming I have the opportunity to raise the total current rents on my duplex ($3000) up to about $4,000 by improving the property and marketing correctly, what number am I taking a percentage of when calculating these reserves? Cap ex and maintenance won't go up if I'm taking in $4k a month instead of $3k. They will likely go down if anything. Property management will likely increase and vacancy will hold constant. 

I realize I'll need to factor in the cost of the improvements that will lead to this increased rental income, but just looking for opinions from folks who may have run into this in the real world and how you've adjusted your reserves accordingly. 

Thanks!