I have an bone stock 05 HFP 150,000 on it. I recently put on a new-to-me low-mileage OEM axleback. I like the look and sound, and they're a decent axle-back for my needs. I don't want to do anything crazy with the car, just want a little more power. I have no plans for the car beyond that.

I got a brand new Megan mid-pipe from a friend I want to put on. The current cat is too far gone to re-bolt up to the mid-pipe. Once it's off, it's off.

Big thing for me - I don't want anything loud. Just a little noise is good for me, that's why I'm keeping the stock muffler. That being said, should I put on some shorty headers with a new cat? I'm afraid of loud the car will be with Race headers/Shorty+Test Pipe. BUT I'm also afraid that pairing shorty headers to a cat is pointless and a waste of power.

Should I just keep the OEM headers and get a new cat to put on the midpipe?

OR is it worth it to get a new shorty along with the new cat? I don't want to waste money on headers if a cat is going to nullify any power gains.