When I hit the throttle hard, a rotten egg smell comes inside the car! I know its from the cats, but how is that possible when the exhaust is exiting behind the car?? Must be a leak somewhere thats getting inside the car????? The primary cats/manifolds were replaced with used ones 4 mos ago and the car passed smog and theres no CEL!!

 

Keeping pushing it until you don't smell it lol

 

You may need to replace the truck vents:

 

You have two options, either go to your mechanic to remove the exhaust system and wash it ( cost time and money but more effective) or check Amazon for catalyst converter cleaner and pour it into the gas tank It will dissolve the sulphur. All the methods work. If you a brand recommendations I did go to with Chevron but do some research ok. Good luck

 

if you have the HVAC vent mode set to outside air, you will certainly smell what's outside similar if you are following a diesel truck. the HVAC intake is at the windshield cowling which is just above the cats!

try to set the vents to recirculate and see if the smell minimizes.

 

Common problem. Rear pressure flaps leaking exhaust into trunk/cabin. More evident with sunroof and/or windows open. Happened both in my 250 and 350 Gen 2 cars. Simple and inexpensive fix. They can be seen inside the trunk after the side panel removal. They are accessible from underneath the car. I did not have to remove the rear bumper cover to replace them.