dose anyone have them? and difference between stock?

 

They are higher voltage than stock. That burns the air fuel mixture more efficiently by producing a hotter spark. There are small gains for a naturally aspirated car. Besides the small power gains the COPs will make your car rev smoother.
If you are forced induction they are good for about 15-20 HP. The best thing is they eliminate spark blow-out which is a big problem with high boost.
They are like 20,000 volts where as stock are maybe 10,000 volts.
The Granatelli Hard Core COPs are like 60,000 volts. They produce even better gains but they had a problem with the coil windings failing. I had 4 of them fail. They improved performance really well when they worked. I switched to MSD Balster COps then. because they were problematic.
JR Granatelli justhad GMS sendme a new set of their new design COPs this last week and I will be dyno comparing them to the MSD Blaster COPs (I am running now) and against the stock COPsthis Spring when I get my car over to Brenspeed. The Granatelli COPs are much higher voltage than the MSD. The MSD have not failed me though yet.