Hi and welcome from Sweden!
The battery flickers on all cars so no worries.
Could be a switch on the clutch or brake pedal.
About the power I don't know, sounds like something serious if you get past by a megane, check if the throttle opens fully, could be a stretched throttlecable. If it isn't you could always supercharge it and cruise past the Audi's and Mercedes!
With a S/C you will get around 420hp, start saving!