I know this is an old thread, but in case anyone revisits this article, I would like to say that if you have a MT-4400, you owe it to yourself to remove the muffler and take a look inside. They must have a wire shooting machine that packs that muffler so tight with catalyst material, that you couldn't possible get more inside without some sort of hydraulic crushing device. Once you get that wire birds nest out of there and open up the exhaust guides, then remove the limiters and re-tune the saw, you'll have a real powerhouse on your hands. Saw has really high compression. I didn't have a pressure gauge for a peanut plug thread, but the saw reminded me of the old Stihl 024 models, and I had two that had compression over 200 psi. Fortunately, the MT-4400 has a decompression valve - thank you Efco! They have generous adjustable oilers as well, and they aren't the cheap nylon pump parts, as they are metal encased. They are surprisingly well built saws for the money. They are rated at 13,000 rpm, but I de-tuned mine a little. I need to hear the four cycling, and that sound is gone when you are at 13,000 rpm.
