Another welcome from Texas..
From the sounds of it, you are not running the right fuel map with your Jardines. It sounds like you are running way too lean.. This would cause the popping on decel.. and make your exhaust header a lot hotter than normal. Triumph's 'off-road' tune is still too lean for the Jardines. You need a DynoJet Power Commander with the appropriate map loaded.. or TuneECU or TuneBoy software to load a different tune to your bike's ECU.
I love my Jardines..They make the Rocket sound like the big bike that it is..
I have a DynoJet PC3 that I had tuned at a local dyno shop and my bike runs great. I do get a little popping on decel lately, but I believe my Jardine's baffles are about wore out. Thinking of going with Jardine's "quiet" baffles as a replacement. They are supposed to be a bit quieter and since they are not glass packs like the original baffles, they never wear out.