How much to replace coils?

[nostalgik]

My rb25 was breaking up at higher revs from time to time. Thinking it was the plugs I replaced them with gapped ones and have changed them again with colder gapped ones. Im pretty sure a coil is rooted. Anyone know how much it is to replace coils on an rb25det. After I tried the new plugs the engine is running very rough and sounds a bit like a lawnmower. NOT HAPPY:mad:

[N I B]

S1 or S2 RB25 or is it running the RB20 coils.