Figure out what you want out of your tire.
First figure out your tire's profile;
Do you accelerate hard while still leaned over, or when your mostly straight up and down?? While leaned over, 55 profile. Mostly straight up and down, 50 profile. One way to look at it is where does your tire wear down the most. Down the center or on the sides.
Next your tire's width;
A 180 is cheaper than a 190, but a 190 has a larger contact patch than a 180. 180s are not made in 50, so if you picked 50 profile 180s are out. 200s are not made in 55 profile, so if you picked 55 profile 200s are out.
Next, don't go to a 180 for less rotating mass. I'm willing to bet a 180/55 conti is heavier than a PP190/50. Different brands are different weights. Weight is largely affected by tread depth. A worn tire weighs less than a new tire.
To reduce rotating mass look at sprocket, brake disc and rims.
If you want to increase turn in, raise the rear an inch with dogbones. Don't buy a tire to help turn in, buy a tire for grip. Adjust your chasis for the geometry you want.
Now that all that is out, I accelerate hard while stilled leaned over and I'm willing to pay $25 more. So I run 190/55.
And yes a 190/55 will increase top speed at the expense of acceleration, not much though. Going up 1-2 teeth in the rear will bring the top end back down and the accel back up.