Going on 2 weeks now. I don't see any reason why this will not last for a while without any adverse affects. The coil is designed to be used with computer controlled systems.
The coil wire modificaion is very simple. I just cut off the OEM connector on the coil wire. Then I reassembled it with the part supplied with the Accel coil as per the instructions.
I went with the Accel because I had installed one in a GMC 4X4 I had years ago. I was very happy with the results back then. Then I saw it advertised on a Turbo Volvo site. So I figured it was safe to use on a modern European ignition system. Funny thing is that they are selling the EXACT SAME COIL for $198. Go figure! Well they do include a bracket for that price. I guess the extra $148 is for the bracket and cost to remove the Accel sticker. HA! HA!
Here is a pic of the Volvo HIGH POWER SUPER COIL UPGRADE:
Hope this helps.