This Malibu was in for some significant audio upgrades, but one of the main concerns was the lack luster performance from the factory woofer. The OEM installed Rockford Fosgate Marine 12" woofer, is actually a quality woofer and can sound pretty good! The issue is, with the factory build enclosure. It has 2 main failures. 1, it leaks air like sieve and 2, its too small even if you fix the leaks. Ive seen some so bad, you can see daylight through the seams. You can see below, the owners past attempts to seal the old enclosure.
OEM enclosure is about .7 ft3 prior to the woofer going in. New enclosure is 1.1. Does not sound like a big difference, but it actually is. A small change in the air volume impacts the woofer's sound and performance. Think about the thickness and tension of the strings on a stringed instrument. You can tune the woofer but adjusting the internal air volume.
So we spec out a new custom enclosure that larger, and of course, air tight. We mate it to the original facade and only end up moving the facade out about an inch. Ends up looking completely original, but the improvement is huge. In this particular build, we had the advantage of freeing up the factory 500W 2 chnl tower amp. So we pulled the original 300W woofer amp and repurposed the 500W to the woofer. So we also gained some wattage performance. Trifecta!
This setup started in about 2012 or 2013 and was found on the traditional nosed boats. On the MXZ's, they just front loaded the woofer to the plastic foot well, and run the woofer free-air. Equally poor execution. These boats also benefit from a custom enclosure.