4 blade or 3 blade

thinking it's about time to replace my 3 blade stainless prop, got a good hole shot and pretty good top end now. what will I gain or lose with a four blade? Boat is a 1998 18 foot Astro with a 150 Mariner EFI.

typically 3 blades are faster than 4 blades.
however every boat is different.

get with your prop guy and do some testing to find out what your boat likes.

or borrow a friends prop