They need shimming and pop testing so they open at the right pressures otherwise you will end up with 8 different injections events and the car will run like a bag of nails. Let a proffesional balance them for ya ! If you do a search online, united diesel does supply/fit and balance nozzles from 54 quid each. You can get even larger nozzles for better performance but it's a bit pointless as the turbo will need upgrading and pump adjusting otherwise it will smoke at WOT. I run Bosio race520 (0.260), bv43 (just fitted it last night had a hybrid gt1749VA before), 11mm pump, ported head and a few more mods and soon i'll break 200Bhp- not bad for a little 90 Bhp VE engine ?!