You do know that your top speed will drop and you will increase your rpms by about 800 dropping from a 19 too a 15. How many rpms are you running now? Hole shot with a 15 would be a big increase.
It will run 6200 and has about 1/2 of the boat still in the water before it blows out as I trim up. I am just testing before I buy to see what changes will come about, but I'm also increasing diameter by 3/4 inch too