Is there any way to increase the current coming from a coil??
and what Is the approx voltage coming out??

 

Is there any way to increase the current coming from a coil??

Do you mean from the secondary (high voltage) side?
I suppose you could run several identical coils in parallel, but that would be dicey.

and what Is the approx voltage coming out??

It really depends upon the coil, and how much power is applied to the primary.

However, I've seen newer ignition coils create sparks that were nearly an inch long.

Air at sea level has a dielectric strength of 3,000 volts per mm. Since there are about 25.4mm in an inch, it would take roughly 76,200 volts to ionize the air enough to jump that much of a gap.

Jumping the arc across a sparkplug is a somewhat different matter. Compression ratios for gasoline engines are typically in the range of 8.5:1 to 11:1. Spark plugs may have a gap of say, 40 to 60 mils (0.040 to 0.060", or 40 to 60 1/1000 of an inch).
60 mils = 1.524mm
If the compression ratio were a nice even 10:1, then it would take 30,000 volts per mm, or 45,720 volts to bridge that 60 mil gap.

 

Is this application to be used in a car? To raise output V of secondary increase primary V; Dump a charged capaciter across primary, like early electronic ignition systems did. I made one late "50's but do not rember values, something like 100 μF @ 300 V.