Been having the same issue, bought a 19 gt with 88k miles and a awe muffler delete came with it. Every wide open pull i notice a smell too, ive lifted the car and noticed black soot building up around the clamps. So its probably an exhaust leak for most people. That or cats but not sure myself...
Dealing with this exact problem lol. Just bought a used 19 gt with 88k miles. Chasing the same problem. I dont have too much info about whats been done to my car other then roush cold air, axle back, catch can and lowering springs. Idk if its tuned im boutta find out soon but if yall find a fix lmk
Im new to the mustang world and muscle world, i just bought a used 2019 mustang gt base model manual. Its got 88k miles and i believe im 4th owner. Previous owners have modified the vehicle slightly, this includes a unbranded cai, lowering springs, oil catch can, and an axle back muffler delete...