when does the stock coil start putting out lower voltage?

 

Here is a tip for anything electrical; they can go bad at any time. Somethings only last 2 weeks, others last forever.

 

ive noticed on a weak coil, it produces a small yellow spark when grounding a plug to the engine block. Also its hard as heak to kick over too.

 

May need a new cap, rotor, wires or any combo of them? Have you inspected them yet?

 

i stuck a new hypertech 53,000 volt coil, cap, and rotor on my car and noticed a huge difference my stock rotor,cap, and coil had over 100k miles on them. also when i got the car 5k miles ago it had the stock wires and everything so i replaced it all and it runs really good now

 

From what I getr from your question, the stock coil stops producing noraml spark around 5500rpm. This of course is . An aftermarket coil will give you more juice through your operating RPM but if you old coil is still in good condition you wont notice any difference in power.
SSC