Cameron,
For Series 1 RB25DET (Wih the ignitor pack) you need "SF-DIS-001" model splitfires.
For Series 2 RB25DET (Without the ignitor pack) you need "SF-DIS-005" model splitfires.
I dont think having S2 coilpacks in S1 car will work. and vice versa.
Hope that helps
Victor