Here is what I did to correct the problem on my B3030. I went to a plumbing supply distributor and bought a copper fitting, can't remember the exact size but you won't find it at Home Depot or Lowes. I heated it up to expand it using pliers to hold it then slipped it over the Kubota pipe. When it cooled it fit super tight. I thought I might have to tack weld it but never had too. Been on for several years now and corrected the problem. I think the piece was about $10.00 +/-. I trimmed a little of the Kubota pipe so I could get the correct angle for the new copper piece. The pipe has turned quite dark so there was no need to repaint the exhaust. Hope this helps.
I done this on mine and apparently the extra weight of that copper fitting caused vibration and the exhaust pipe broke off just past the last muffler bracket, not sure if it is heating up a wire loom on the frame there. Will be keeping an eye on the thing, might be harmless the way it is.