ORIGINAL: madman75
I found the same thing. I had to retune the LS and HS needles. The engine ran consistently better with the muffler. Also, the needles seem to adjust better.
Yupper...thats what I found also. It is going to be very cold here tomorrow am...going to see how my MB290 Gas/glow engine starts!

THIS IS Monday the 27th. Darn cold but engine starts very good yet!