I recently went stg 3 but i've been experiencing a plethora of problems. The d/p came loose, completely, I had to retighten and add lock washers, and now it seems like the car is running too lean. Of course this is a qualitative analysis as I do not possess the means to quantify how lean but the exhaust gas exiting the muffler is extremely hot, as well as a crackling/ popping sound coming from inside the muffler. I don't know how much of the is attributed to the free flow cat or not. Please if anyone has any insight please enlighten me as I am at the end of my rope with stg. 3. TIA.