hello I'm new here and mostly new to Subaru world,this is my first Subaru ever but not first time working on one. Bought a 2011 Subaru wrx premium wagon about 6 months ago at 105k mile. It already been slightly modified by previous owner stage 2 with FMIC and full exhaust / intake setup and custom pro tune with Cobb acessport. along with some grimmspeed stuff EBC, light weight crank pulley, AOS. I have just reach 114k mile, few days ago at late night when i pulled into a empty lot to park up to eat my dinner it started making " cardboard box of rocks" like rattling sound so i slowly drove it back home and parked it. so i started looking into the noise issue next day and was reading that it could be timing belt tensioner going bad or rod knock. So i gotten a new timing belt kit since it still had the original timing belt on it. swapped it with new belt and tensioner. still made the noise so i figured OK it most likely something went wrong in the bottom end. next day i got started with draining the oil and dropping the oil pan to see if i can find any play in the rod bearing. the oil it self had small small amounts gold metal flakes and looking in the oil pan there was some some of gold flakes. Most of the gold flakes was on the windage tray. I checked each rods for slight bit of play, non of them have any movement or play on them not even slights bit. so i had a friend turn the crank slowly back and forth see if we could get it make slight noise or feel a slight play but nothing at , like as if there's absolutely nothing wrong with them. could this still be really early stage of rod knock or bad main bearings making that "cardboard box of rocks" sound, trying to pin point this issue asap so i can get back to working soon. I made some videos on my iphone