Theoretically, but for almost all boats the gain is too small to be noticed. The exceptions are probably racing boats, IE those that need every bit of performance they can get.
Most people just put through hulls on to make noise.
Yep, aint worth the effort, and its just more noise..(doesn't bother me, though, as I like fast noisy boats...but lakefront owners and others will hate ya)
I had a 20 foot Baja with thru-hull and a 5.7 Mercruiser for 10 years. I loved the sound of the V-8 at wide open throttle and never really realized how noisy it was. Even though the exhaust exited under a swim platform it was noisy. I now have an outboard and am amazed at being able to have a normal conversation with the passengers without having to yell. I really don't miss the loud thru-hull, but then again I am getting older.
Depends on the motor. Mercury recommends thru-hulls for max performance with a big-block. The exhaust passage through the outdrive supposedly becomes a restriction at high flow rates. I would think that a built small-block (over 350 HP or so) would have the same flow issues.
That being said, my 425 HP, 496 HO has switchable exhaust (thru-hull or thru the drive). I can't tell any performance difference (GPS speedo) except noise (but it does sound neat.......) when it's running on the thru-hulls.
