Thanks a lot for the compliments!
Yes, a CEL is likely since the catalytic converter is eliminated. A CEL fix can be used to cure that. We don't currently have one available, but I am hoping to have one soon.
The tube is 2.5". I looked into using a 3" tube, but then the downpipe wouldn't have been a direct bolt-in replacement like I wanted it to be. There is plans for a all-out performance downpipe with a bell mouth inlet and large diameter tubing, but that won't be released anytime soon and the price definitely won't be $175.