Whatever you wanna call it, just bolting up a V2 muffler makes a big difference over the old one.
As it should do - it's a factory muffler mod.
Another thing to consider when it comes to porting - now it doesn't matter so much what saw you get. Husky, Stihl, Echo, Dolmar, etc etc. You get whatever you can afford, or has good parts or service locally, pick your metric. Stock specs matter very little so long as the build quality is there. If you can get an Echo 7310 for $650 delivered, and if you can port the saw yourself, 70cc dyno threads mean very little. Even mildly ported, it's gonna make your job much easier. If it is easy on your bank account, all the better.
Which leads me to another point Huskyboy touched on. A saw doesn't have to be ported to within an inch of it's life to be valuable for work. If you just do a simple woods port, like the REAL woods port where you simply add some width and go easy on the timing, and maybe add some ignition advance and remove a gasket, the things will run well enough to improve your life. It won't win every GTG, but it will start every time you need it to, and the amount of fuel it burns won't upset you. In the end, maybe all ya need is a muffler mod.
My Dolmar 420 is ported, and runs strong. The last one I ported for someone else has 6* advance. Mine doesn't, and is ported more conservatively. It just gets the job done as it is.
It sort of reminds me of a time long ago, when a Norwegian man spent a good deal of his spare time demeaning Echo chainsaws that he had never used. Meanwhile, I was using an Echo 520 in logging and landscaping in England at the time that I had ported myself after paying $100 for it because it was the first 50cc chainsaw I saw for sale before literally hopping on a boat to the UK. When I checked her over and she looked great, I bought it because I knew I would get it to run how I needed it to regardless of her stock performance. When you already know you can port the thing, your options for a used saw can be wide open, especially if it is a common brand. And I used that thing to do stuff you usually do not ask a 50cc saw to do...