I have a 2013 Abarth fine settimana car with 83,000 miles. Its misfiring on startup. I changed the plugs (that needed doing anyway) but the cylinder 4 misfire has returned, so Ill change out the coils. Anyone been thru this? Should I replace with stock or upgrade? Any suggestions re high-performance products? The prices for high-perfect are a bit shocking, are they worth it? If I choose hi-perf do I reset the spark gap? What is torque for plugs? Any advice on this job? Thanks for sharing your experience.