Anybody installed this slip on? Got mine yesterday, and in looking it over, I noticed a threaded hole(about 5/8") in the link pipe. I'm pretty sure it's for the Euro-spec oxygen sensor not required on US models. Can someone tell me how it should be plugged? I've e-mailed the company in England, but don't know when a reply will be forthcoming. It's a beautiful set, but contains no instructions. No sense starting to install until I can deal with the hole. Thanks for any input.