No, i'd taken them out completely, left gaping holes to atmosphere on each cylinder, ran fine. :p 
Yes, they were unplugged, had put new ones in and had to rush to finish the job, forgot to wire them in. 
Fair enough, maybe i was lucky. All i know is i drove around with it like that for a couple of weeks in bollock-freezing weather and didn't really notice the difference, sure it was a bit rough first thing, but that was normal lol.
Cully, i'm not saying they aren't used on an HDi, just that they don't appear to be necessary, in my experience anyway.
Yes, they were unplugged, had put new ones in and had to rush to finish the job, forgot to wire them in. Fair enough, maybe i was lucky. All i know is i drove around with it like that for a couple of weeks in bollock-freezing weather and didn't really notice the difference, sure it was a bit rough first thing, but that was normal lol.
Cully, i'm not saying they aren't used on an HDi, just that they don't appear to be necessary, in my experience anyway.