I wouldn't bother if I were you. 90% of the stud & nut conversion kits out there are total shite. I bought some around 2 weeks ago off Demon Tweeks - the Grayston engineering ones which are meant to be one of the better makes, and quite frankly they weren't very good quality at all, so I managed to get a refund as I didn't even fit them in the end.
On some of the other forums - 205 drivers in particular, there are a lot of threads about wheel stud and nut conversions, and also many horror stories! Some kits out there aren't even made from 8.8 tensile steel which quite frankly is awful as even standard wheel bolts are 10.9. I would only ever go for the peugeot sport ones now if I was going to do it, or get some that are the same quality - theres a guy that got some made up on 205 drivers which are an exact copy of the pugsport stuff at half the price!
Danny_gti off here said the Rally Design ones were crap, hence being cheap. For 16 studs and 16 nuts of the pugsport from special tuning your easily looking at £150+ which is about right in terms of quality as they are 12.9 grade steel, the studs have rolled threads and not cut threads which helps them not rounding off. Remember, if your studs did happen to fail and snap like some already have, imagine the damage it could cause - it wouldn't be nice thats for sure. I decided to stick with OE wheel bolts as couldn't justify spending so much on a 'quality' stud conversion. So what if it takes a few minutes more to change a wheel, at least you know they won't fail you lol!