Thats a hard question as it depends on your gear. But I’ve seen a doubling of suction on some setups with less blockages and the ability to run your engines at lower rpm.
On a dredge like a dredgenz dredge ive seen a easily a doubling increase in suction
On the Keene setup like the 4 inch you can easily get 25% and on the 5 and 6 inch setups about the same.
On the Proline setups usually a 10% increase as they are pretty efficient already