I run a single box (magnex) de-cated exhaust on my Audi 80 tdi with no real sound increase, but interestingly the turbo now spins up loads quicker and earlier, from as low down as 1500rpm, this due to the decreased back pressure I assume, I've been thinking about running an open system for a while now as just the other month the center clamp broke splitting the system so it was unsilenced,
I thought it sounded great!
& as for '2002gimp' about diesels sounding awful..
honestly.. I would have the sound of a four pot diesel over a four pot petrol anyday!!
Tust think how quick the turbo would spin up if it was fitted at the back of the exhaust with no back pressure at all
now see that'd be mint... sorting the boost pipe work tho, that would be a bit of agro ... haha ;D ;D