Definately coil packs, fitted Splitfires and iridium plugs to mine today. My engine light had been on for a week and a half but like yours had not yet shown any signs of hesitation or missfiring yet. Just ran the engine, no engine light on and appears to be running much smoother and cleaner than before.
Splitfire coilpacks, part# SF-DIS-008, Brought them from CRD in NSW for $510 delivered, awsome service as they arrived a day and a half after payment.
NGK Iridium spark plugs BKR5EIX-11 $90
Also have NA R34 Good luck, Nath.