Congratulations, how is throttle control and idle? Does it overrev in grasscutting mode?
Sounds (!) like the exhaust has either a rupture or it's in need of stuffing. I was fortunate to have a couple of spares last time I swapped one over. I just used needle nose pliers to pull out the mesh stuffing from the old one and put it into the other. They are fiddly to put back on for a novice but the key is the angle you do it in. There are plenty of youtube vids on the subject.
This is a good one to watch.
Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!
