We have an Echo CS-370, and posted quite a bit of info about it.
Right out of the box it was WAY off the mark for carburetor settings. I had to add fuel everyplace, it wouldn't even stay running.
The airbox has a provision for cold weather operation, by moving a rubber block to allow some hot engine air to warm up the incoming air to the filter. Takes about as long to make the change as it did to type this.
The CS-370 is not an overly fast cutting saw, or a high speed engine by design. It is however, a very strong mid-range engine. I quickly installed a 14" bar on ours, which it is very comfortable with compared to the 16" bar it showed up with. Plus it takes the same chains as our CS-360T, which is also 14".
Recently, I did some timed cuts with our Husqvarna 55, Shindaiwa 488, and Echo CS-510, in a dried Cherry log, and posted the results. Made 5 cuts with each saw and timed them with a stopwatch, the Echo 510 and Husky 55 were dead even, the Shindaiwa lagging about 10 seconds behind for 5 cuts.
The next day, when we got down to a smaller part of the log, I ran the CS-370, just for fun, and timed 5 cuts. It actually cut FASTER for 5 cuts than the larger saws, the only difference being about 2-3" less diameter of the cutting material.
Those little low-profile 3/8" chains are pretty impressive, one wouldn't think the little CS-370 would even be close to the larger saws.
Ours responded quite well to the muffler mod, I added a couple of pics, showing the unique porting and the location of the catalyst which we removed. I opened up the 4 larger holes under the catalyst, but it's difficult to see them in the pics, then the exit hole and deflector were modified a bit.
As for the quality of Echo products, I have owned or own just about every single peice of power equipment they make or have made, and haven't had the first problem one with any of it. Our garden tiller, leaf blower and string trimmer have seen considerable use, as well as the chainsaws we own or have owned, and to date I've never replaced an single part on any of them.
The only problem I ever had was that one of our CS-510's was shipped without a filter on the gas line, so it ate a piece of debri, and required a filter added and quick carb cleaning.
Echo chainsaws in particular get a bad reputation for two basic reasons. They make/made a LOT of low powered/pathetically anemic reed valve engines, CS-300, 301, 3450, 346, etc. They are OK, but we've owned them and they are SLOW. So slow you can go back in the house and have another cup of coffee and a donut before they'll make it thru a 10" log!
The other BIG showstopper is that Echo is aimed at pleasing the EPA before the consumer. Without exception, every single saw we've got in here for repair or purchased, has required custom carburetor settings, ie, removing limiter caps and ADDING both low and high speed fuel. As mentioned someplace else above, the respond quite well to muffler modifcations.
I can see why they get some negative feedback in being low powered and smoking P/C's on occassion. Our CS-360T wouldn't have lasted through the first outing it was so lean. It spent all it's time on the rev limiter and was SERIOUSLY lacking it power until we added some fuel clear across the load/speed range. It's been cutting on nearly every outing now, and still hasn't developed the "death rattle" they are somewhat famous for.
Anyhow, my opinion, the CS-370 is a decent little saw, but it is just that, 36cc and a clamshell engine design. Decent power, both nothing overly impressive. FWIW, the CS-440 is a much better saw for a small jump in price. It's happiest with a 16" bar, the CS-370 and 400 are going to like a 14" bar much better....hope this helps some?.......Cliff