Yeah headers and y-pipe for sure. I put a test pipe on one of my mazdas for a dyno session and wasnt impressed with the 2hp difference considering the risk of having the car impounded after getting caught by one of the roadside sniffers.
I would never suggest taking out the main cat. I got nothing but rasp when I did that. I put a high flow from trubendz in there instead. What Magnaflow muffler are you using? I'm planning to do the same thing very soon.
I never looked at the video because i don't have sound at work and they don't like us going on youtube. Also some are running magnaflow mufflers in that spot and not resonators. I myself am looking into the Magnaflow Turbo XL 13215.