My MS 460 has an adjustable oiler too.
It just didn't give enough oil on larger bars even when turned all the way up.
And when I read that MS460's sold in the Pacific Northwest where they cut down larger trees, came STOCK with the high output oiler (part# 1128 640 3250), I found the part number and put one in my saw.
As to the muffler, I found from people overseas who had the MS 460, that their saws came stock with the Stihl dual port muffler (part# 1128 140 0616).
In the USA we had the more restrictive muffler to meet USA noise standards, at the cost of running hotter with less power.
I don't consider what I did to be hot rodding it, just using stock parts that are normally sold on this saw in other places.
On the site I mentioned in an earlier post, the people have a modification to the stock muffler that allows for easier exhausting. They also have work to improve the carb. That is why I called it hot rodding. Maybe the term isn't correct. But the changes they discuss make the saw more powerful and easier to use.