Short answer, probably not. Long answer, it depends.
I wouldn't count on an internet speed boost, mostly because there are so many factors outside of your control that can cause internet speeds to vary and you've said you can hit the max that your ISP provides. What these are intended for is to increase speeds at further distances. If you're relatively close to the router this likely won't provide you with much boost.
If you wanted to run some tests, I'd do the following:
Get some form of network storage device and test the data rates for the following situations:
1 - Directly plugged into your computer (Ethernet)
2 - Both the network storage and your computer wired to the router
3 - Network storage wired to the router with your computer on WiFi.
Find some data on documented data rates (not manufacturer propaganda) for both your WiFi card and your router and compare them to your results. If you're close to expected rates then you'll likely see no increase with new antennas. If your speeds are off by a fair amount, but your wired and wireless speeds are close then your computer or I/O device may be the bottleneck and it won't really tell you much of anything. If your speeds are way off and your wired connection is higher than wireless I'd look at your signal strength, see if your router or computer shows your connection speed and if they're both low then you may see a speed increase with new antennas.
You can also connect your computer to your router, via Ethernet, and test internet speeds, but since you're already maxing out on WiFi you'll probably see similar values between the two which is why computer to network storage is a better test.
Hope that helps.