Hi, I am curious about Rcexl ignition Model: A-02 which voltage ranges DC 4.8V to 8.4V, I was wondering if anyone tried this Ignition with 2S LIPO (7.4V) ? any danger of frying the ignition with 2S LIPO ?

Anyone ?

Neither Im a user nor an expert on this stuff, but what I can tell you is technically a 2s holds charge at 8.4V when its fully charged and can be discharged upto 6.6V safely. So given the specifications of the product you mentioned, you can use it for your purpose.
To be on the safer side, just check the voltage of the pack before using it.

Thank you, what worries me a bit is that most of these ignition systems are limited to 6v -7v but this particular model has a label printed  4.8/8.4

You can use a Turnigy Ubec, it has option for 5&6V and can work from 2S to 5S lipo.

http://www.hobbyking.com/hobbyking/store/__4319__turnigy_3a_ubec_w_noise_reduction.html

Or you can use 5V regulators or diodes,can read more @

http://www.rcindia.org/servos-gyros-and-all-electronics/servo-voltage/

Thanks