Backbox deletes on diesel cars are never a good idea, from someone who's had one.
Imagine farting through a straw into a bottle of water, yea that's what it'll sound like.
Completely disagree, I have run the following;
MK2 Leon FR PD170 , 3" straight pipe from the turbo
MK2 Golf 1.9 TDI AHU, 2" straight pipe from turbo
MK2 Leon FR PD150, 2.5" straight pipe from cat, I will be changing the downpipe soon on this as well for straight through.
They all sound a lot better.
Back box delete on the CR150/184/190 isn't going to massively different either as you still have the DPF in place which will soak up most of the noise.