What do you use the air compressor for? If not for spraying or running rotary tools (disc sander, etc), downsize to one of the quiet 2 gal compressors from HF. (Fortress, about $160 but cheaper on sale and with coupon.) They weigh about 40 lbs and store easily under a work bench. They work well for blowing off chips (oil less), and have plenty air for running a brad nailer, staple gun, etc. Put the 20 gal in the garage.
If using for spraying, etc, then move the compressor outside into a small closet enclosure and pipe to inside. A gain in space and reduction in noise.
If using for spraying, etc, then move the compressor outside into a small closet enclosure and pipe to inside. A gain in space and reduction in noise.