Probably the most important single change one can make with a 2240 in terms of noise at the muzzle is reducing hammer spring strength. Either going to a slightly lighter gauge spring, or carefully clipping off 1/2 coil of the stock spring at a time and testing until the noise begins to reduce. The problem with 2240's and excessive noise (and they really are loud, especially indoors) is that the barrel is too short for the large volume of CO2 dumped by the rather heavy (about 65 grams) hammer weight and the strong, long spring. Reducing the spring a bit at a time (remove rear plug, clip spring, reassemble) you will soon find that the amount of CO2 'cloud' appearing after the pellet is reduced, as is the report. After the initial reduction in noise/waste CO2 it becomes a matter of individual requirements in terms of just how slow you want the pellet to go. Clipping a little bit of spring at a time and waiting for that drop in noise shouldn't cost more than 10 to 20fps so still plenty for garage or garden plinking. THAT is the point at which you add a silencer, as the reduced volume of gas escaping after the pellet will be much easier to quiet with just about any silencer, even something relatively simple and compact. Quieting a really loud pistol would be much more challenging.