Wideband O2 sensor bung.
Ah ok thanks, I couldn't find anything about it and the chat support at HKS was no help. It's been on the car since my tune and my tuner put a bolt in there but I never knew what it was for. LolIt's a second Bung for an aftermarket Wideband O2 sensor. You can do one of two things: Buy an aftermarket Wideband O2 gauge and sensor (AEM, Innovate, Defi, etc.), or buy a bung plug to screw into the hole until you do buy a gauge and sensor. Either way you can not leave it open as it is now, while it's on the car.
Dyno operators usually use an Exhaust Gas Analyzer (EGA) that is inserted into the tailpipe.I believe my tuner just plugged one in for the tune but I'm not sure. They're an excellent shop though and I'd recommend them for people in the KY OH area
Sounds good, I have 2 more questions as well. After the exhaust components are installed should I play it safe and get the car towed to my nearest tuning shop, or drive out of boost to the shop?All 3 at once is the most effective way to add output and make the car blatantly illegal anywhere in the US. That's why people prefer doing all 3. Whatever you do, don't modify the exhaust without remapping the car. The up pipe doesn't need a reflash but anything aft of the turbo does. After 12 years the bolts will fight back so have band aids on hand and you'll probably want to do everything while it's all apart anyway.