That would be a cool pick of the motors

Noise laws don't restrict equipment, they restrict noise. The Coast Guard restricts equipment. If it's OK by CG regs and the noise is below requirements, you're golden. But, the direction your headed is 180 degrees the wrong one. Those headers are for making power in race boats, with no consideration towards sound or legality. They are that length because there's no physical way to craft a water-cooled marine header and have equal size and flow runners and proper collector length and still dump horizontally through a transom.

it's ok in kentucky....no noise restictions at all on lake cumberland....

Unless you have blowers, the 4-pipes are going to be drastically down on power vs. a header with a collector.

True dat. Way down. The only reason they use them on motors is because the motor needs the quickest easiest way to push the exhaust out when running a blown deal at high boost.

Yeah but they sound really cool and in this narrow hull with 540cu engines, there just wasn't room for anything else.

Jesus. What is that thing, a 6' beam?

A super cool stretched magnum.

It's a 34' Phantom - built in 1995 and still racing in Trinidad. Just short of 8' wide.

Geez, Ron - Most of pictures of that boat that you posted showed the engines 20' under water.... :D