I can confirm that the Milltek un-resonated centre P/N MSVW259 fits to the standard front pipe and to the rear
K1 (Remus) pipe. All you need do it cut about 70mm off at the Remus backbox join.
The standard
Cupra/
K1 centre slides into the
K1 Remus rear pipe where the rear pipe it flared to accept it.
Just cut the flared section off (it's around 68.5mm OD) and you are left with a 66.5mm OD which slips neatly into the MillTek which has a 69.5mm OD & 67mm ID approx. You just need a good 69-70mm clamp to hold it all together (the original clamp is a touch small and won't clamp up tight enough to prevent exhaust/joint movement).
Sound wise, it has certainly made a difference, as you can now at least hear an exhaust note.
Idle and cruise is only marginally louder (if anything a touch less resonance as it drops to idle), the main benefit is a nice OE sporty note at around 3,500rpm.
It could do with a little more volume above 4,500rpm but I guess only the full MillTek will release that soundtrack.
Overall very please as it sounds very OE and not OTT at all.
It cost me £120 for the new MillTek, but I was quoted between £100 and £150 from two local stainless specialists to provide and fit similar. And as much as £223 from Powerflow Bromley.
However, I am sure I will soon get used to it and want more.....much like the power game !!!!!