My '01 Response came with the same Primex silencers that pretty much every Response prior to 2015 had standard. There was an optional quieter version that included a crossover tube to take the edge off the opposite banks firing, but most did not order this option. These stock silencers are hardly better than straight rubber tubes. They sound and flow great, but the sound out the back can be intense and it carries across the water a long way. As I'm often on the lake as early as 5am in the summer (public water, lack of sleep is necessary evil), I thought I'd try to see if I could quiet the boat down a bit without much effort. I had seen on another site that folks had success with this modification so I thought "what the hell?"
For 40ish bucks at Home Depot, you can pick up two 4" Clay to PVC Nibco couplers and a pair of 4" to 3" ABS or PVC closet elbows. If you have a Malibu with a Wedge, you will need to shave the Nibco down a bit to fit over the outer ring of the standard exhaust port. I just did a rough cut as a proof of concept (thus the rough appearance) and eyeballed how much to cut off to get the outlet to be right at the waterline when underway. On my boat, this meant pretty much cutting these off 1/8" above the 3" flange.
Both the volume and intensity of the noise is reduced inside the boat (I have insulated motor box so most of my sound comes from the back). You hear more of the motor thrum and not so much of that slapping type sound you hear from each bank firing. Conversations are easier when underway.
The biggest change is behind the boat though. I never paid attention to or realized how loud my boat is, especially on holeshot, until I couldn't hear it. I haven't stood on shore to hear how it sounds but presumably if I'm not hearing the boat as the skier, people on shore aren't being treated to the V8 symphony like they were before either.
There is no exhaust restriction with this modification and nothing is dragging in the water. There are no additional baffles. My WOT RPM with these was actually almost 100 RPM higher than without (different days). Top speed was slightly better than previous run.
The only thing to be careful of when installing is to make sure you don't push the elbows up tight to the hull if you're leaving your flappers in (I did to protect against inrushing water but you could probably remove them). Give those enough clearance to do their job.
Next step is for me to clean these up a bit and take them from POC to Production quality. I need to shave the port tip a tiny bit as it was very slightly dragging and making a small spray. There was no impact to wake quality. Wake still excellent at the 28 and 32 off I skied yesterday.
boats are like girlfriends you love them however there is another one around the corner - bananaron, July 21, 2020