All the saws you have there are the better Husky saws. The 376 is a mean beast, and the right size for just about anything. And it has an inboard clutch... which is my only real complaint about the 346. You can muffler mod them really easy yourself, and even lightly port them yourself with a Dremel tool and some grinding bits. On the Stihl side, I have muffler modded most of my saws, and lightly ported several. Muffler mods usually entail drilling more holes in the mufflers in the right places, or changing muffler parts to add more holes. You can do a search on this site and review the mods on all the saws you have listed. Each one has their own recipes for modding and porting. Porting has many levels, and there are various recipes for porting. It also depends on what you are using your saws for. Generally work saw modifications have lighter porting and race saw mods are more radical and designed for running for shorter durations.
You can easily open up the muffler and do a light port by slightly lowering the cylinder height and widening the exhaust ports. Retune the carb after doing that and you can get significant gains. There are two basic methods to more radically port a saw after that. At a certain point of lowering the cylinder height the piston will slap the cylinder at TDC. To compensate for that, you can either cut a ring around the outer top of the piston and make it into what is called a 'pop-up' piston. Or you can mill an area from the top of the cylinder which is commonly called a 'cut squish band'. After that, both methods involve cutting the base of the cylinder, and both methods will increase the compression, as well as change the timing of the ports. Changing the port timing often times creates a saw that runs worse than stock though (depends highly on the saw design) because of the drop in the entire cylinder (including the ports) compared to the stroke of the piston. So to account for that, the ports may need to be modified. Depending on the saw, you may need to raise, lower or widen the intake, exhaust, piston, and transfer ports. This involves port timing, and gets rather involved. There are many threads on port timing on this site. You can also advance the ignition timing, re-jet the carbs or change to larger carbs and boots, as well as do some other things to get more power out of a 2-stroke.