Originally Posted by wydopnthrtl
The only increased noises a **open filter** (brand doesn't matter) will give are:
1) A deeper howel at heavy throttle.
2) A hissing sound at lower rpms. Mostly noticable at cold start.
I would agree but on rangers they do make some type of thump like the OP is talking about, its normal as far as I can tell. I have 97,000 miles on my truck and put an intake on at 30k miles, no issues yet.