Most panel replacements are placebo without a remap. The only benefit being you do not have to replace the filter (negated by having to clean it though in some ways). You will get the same response increase from a new paper filter, any extra power would need a remap as the ECU simply adjusts itself depending on the amount of air coming in.
In theory the engine may not have to work so hard (at least to start with), but you don't actually get any more power as the ECU will not allow it. I had a K&N on my Fiesta and it made no real difference, just makes you push the accelerator harder because you think about it, lol.