Who cares???
The noise makes me smile.
I couldn't give a monkeys about 2 bhp. I'm not a dyno freak or a figures bragger at the pub.
I get in the car give it a bootful and smile like a lunatic. So what if I lose a few bhp.
Do whatever you feel is right. If you like the noise get intakes, if you think you'll feel 2 bhp difference then get panel filters.