Well I'm liking the sound of the MIlltek/HFCs thus far, but I've only put 150 miles on them. I would say it's a good balance between motorway quietness and a sudden roar upon flooring the throttle, which is precisely what I wanted. There is some wooshing and hiss from the HFCs but it's far from intrusive and actually quite cool. There is a little bit of rattle and rasp from the Berks from time to time but it's a "feature" of the design according to Tarmac. The overall effect is great and the exhaust now sounds much better accelerating in 1st (which is the major weakness of the OEM zorst, IMHO) and whenever you're WOTing it.
Difficult to say what difference the Uprev has made though (gained 10whp, 7lbft). The car feels fractionally sharper and more responsive in the lower gears even if the dyno graphs point to virtually zero difference. Not sure if it's a £400 upgrade TBH, but I need to spend more time driving the car in drier conditions because the rain may have been affecting traction. Power increases were also limited by virtue of the insurer refusing to cover a plenum spacer and custom airbox.
Visually I'm a little disappointed that the Milltek's tailpipes aren't as polished/shiny as the OEM pipes nor are they slash-cut, which suits the aesthetic better.
Oh and great service from Abbey as usual
DT