It is a great idea to increase your investment amount as and when your salary increase. This is a proven way to get financially free sooner.
If you keep your expenses as much as possible at the same level, then the savings % automatically goes up. Many people fall prey to a lifestyle inflation which keeps them on the corporate treadmill aka rat race.
To sum up, I’d say increase your SIPs such that 50% of your income hike goes to SIPs. Its like a good EMI (cliche). While doing this, ensure that your funds are doing well, and that you are invested in Direct Plan Mutual Funds only. You then get upto 40% more in long term portfolio size by avoiding commissions and brokers.