Ive never had the Downpipe with my Cat back milltek, when it was new at around 3000rpm in 6th, the exhaust did have a slight boom to it, but now with several few thousand miles down the line, the boom has gone completely, perhaps its a characteristic of having the downpipe with this setup makes it too loud to bear with for some.
Sounds like the perfect Milltek setup without being too loud would be TBE resonated which will see slight performance gains, and echo what Hurdy has said as to what the blueflame would sound like as it doesnt have a rear silencer unlike the milly, so can only be a louder system. Looking foward to the 6th June at Superchips to see/ hear one.
To get a real good idea about modding your Edition30, it will be the place to be, and be able to chat with all about their thoughts and experiances. Will be a Great day to remember.