The reason your noise level is as high as it is is simply one of muffler size in relation to the exhaust manifold square area.
The large trucks have huge muffler systems that are either exhausted through the upright mufflers or the exhaust is disharged with piped system under a dump trailers body to keep the dump body hot to aid in discharge of material like collected and dumped snow from parking lots, sand, or asphault.
The small mufflers are small only because of the placement issue under the Kubota model you have and the position of the rear exhaust pipe under the open station of the s.c.u.t. frame.
It is entirely possible to employ a larger muffler under the open station of the tractor BUT the problem with ground clearance is the major issue if the muffler is larger in diameter.
Saying that; if the original muffler was removed and taken to a muffler repair shop with an additonal new muffler they could be paired with a Y fitting and soldered or clamped together with muffler clamps and then reattached with a third clamp and muffler rubber mounts for the tail pipe.
Further a replacement muffler with an exhaust gas purifier to clean the exhaust and only discharge CO2 and water vapor is possible and easily done as well and can be obtained via mail order from an existing supplier that I can PM you with for their contact information if you would like to chat with them.
You will need to provide the model number and cubic inch displacement of the three cylinder engine to order a second muffler to pair or replace the existing one with a larger muffler pack.
The major issue is that these O.E.M., mufflers are of single pass design reducing the exhaust noise only once prior to exiting the muffler.
These same motors in other applications are much quieter as different mufflers are used;
The folks I have mentioned w/o naming them can provide the lower decibel mufflers offered as standard equipment on generators, light towers, pumps, and construction machinery using these Kubota Engines.
The BIG issue is both ground clearance as well as available implement clearances if you have one of those-UGH!!!; belly mowers, as the muffler passes right under the open station and over the belly mower as well as the loader frame mount and snow blower mounts etc., and must be clear of the hoisting cylinder and the levers and arms used to create the amount of lift needed for the implements used with this and other brands of S.C.U.T.'s, and C.U.T."s.
I do not have a nickle invested with them, nor am I connected with them financially in any way, so I can freely offer thier name to whom ever wishes to contact them about better mufflers with or without exhaust gas purifiers.
