I bought the DC Header with the 2.5" collector yesterday. First of all, it's only 2.25" ID. They include a separate flange that has an ID of 2.5"What the hell am I supposed to do with this flange? The instructions say nothing about this flange. The DC Sports B-pipe is 3/8" shorter (the thickness of the additional flange) than the stock B-pipe. How the hell do I get it to fit? If I put the flange between the B-pipe and the cat, the bolts from the cat aren't long enough for the additional thickness of the flange, not to mention there's not an additional gasket which would be needed to do this. I feel like a complete idiot not being able to install a header even though I've performed an H22 swap into my Accord and a wire tuck already. I can now understand why people hate on DC Sports headers. If anyone knows why the B-pipe is 3/8" shorter, how to get around that, or what I'm supposed to do with the extra flange, I'd appreciate the help. Thanks.