Hi Scotty. I bought a used car for my work site, which is over 2000 miles away from my home in TX. That being said, I don't even have a 10mm socket to change the battery, but I managed using road trash. The car has a rhythmic huffing sound when accelerating through lower speeds to higher speeds. I really notice it from outside. It's like a gentle tick/air huff from when heard from the outside and like a lawnmower at low power from the inside when going from a stop to driving speed. There is a very slight initial hesitation from initial acceleration. Comparing it to an identical 2005 Civic, the engine on this 04 Civic definitely has some issue. I made one video to demonstrate. Please turn the sound all the way up and listen to it from Idle to acceleration. There's no check engine light but I'm taking my OBDII Bluetooth cellphone scanner so maybe there are impending codes.

Could you internet diagnose and speculate what it could be? I hate going to a dealership or mechanic at a place I only visit for work 2000 miles away and not having a clue what is wrong!

well, some sort of bearing it going out, pray it's not internal to the engine. Remove all fans belts and if noise goes away, figure out which pulley it is. good luck

Scotty, thanks for the reply. Here's a video under load and

Here's what it sounds like when accelerating. It sounds really harsh.

Well, it turned out to be the catalytic converter.