All I have installed so far are upper and lower ETS intercooler pipes, GFB TMS Response BOV and a 3 inch turbo back exhaust with a 200 cell HFC. I have a defouler on the post cat O2 and about the put one on the pre cat O2. I just changed the plugs with OE replacements. When I really get on the gas at any RPM I'll register somewhere around 20 KS. Could it just be the O2? Or do I need colder plugs? I'm not sure what's going on if someone could shed some light for me it'd be greatly appreciated!

 

Do NOT put a defouler on the pre cat O2 sensor. Did you tune it after installing all these parts. If no, get it tuned. If yes, post a log of your issue.

 

Is your car tuned? If you think the tune is all OK then I was see if anything is causing some flase knock. Exhaust hitting the motor, IC pipes hitting, stuff like that.