For a 737-700 with any thrust rating available (the max you can buy for a -700 is 24k) when you push the thrust levers fully forward you get 24k
for a 737-800 with any available thrust rating when you push the levers fully forward you get 27k.
The reference to this is in the FCOM vol 2 (from memory)
I'll look up the page references later and edit the post....