Interesting how differently a mod can go. I took less material off the front plate than you, but more material off the rear assembly. Mine woke right up, too, and I'm thinking about pulling a bit more off the front port and drilling out the rear assembly just a bit more. The rear port on my mod has a 1/2 inch hole drilled in the center with four 1/4 inch holes drilled around it, where yours is a single uninterrupted removal of material.
I think I'll pull it apart and post pics tomorrow.
A further note: Because the 290 is so popular among homeowners and occasional woodcutters, and because there are plenty of folks on AS who own and use them, I think it would be useful for all of us who have a digital camera and have done a muff mod on the 290 to post our pics in this thread. When I was looking at doing my mod, I used the search feature intensely and found a lot of useful info, but it wasn't until an AS member PMd me with pics, and folks answered some specific questions about how to pull the limiter caps that weren't adequately explained in other threads, that I fully understood how simple this was to perform. Pulling the limiter caps on the H and L screws so I could retune was actually tougher than doing the muff mod.
With some more pics and how-to discussion, this could be the definitive how-to on the 290 muff mod, not to mention the other Stihl models that are similar enough to the 290 so it could cross-pollinate.
Yeah, I know, I know, the 290 ain't no pro saw.
