Just want to know, Is it better to leave the existing filter box with the air filter or the pod filter in the engine bay with hot air intake under the bonnet?
If you're asking if it's better for performance, then leave it as is. I only chucked my pod on for noise, and it's definitely more sluggish under stop-start and hotter conditions.
I only did mine for a little extra noise, which it provided, and I'm happy with it.