I've used the MSD blaster external coil on my C1 for about 3 or 4 years now. Never had a problem with it and it didn't really give me any more power. It made the powerband more efficient and smooth, imo.

The con that I found, is that you have to use a proprietary distributor cap and they're not available everywhere. I'd get 2 caps if you go with the kit.

jmo