Exhaust smell in cab through AC

[2015 High Miler]

2015 Sierra SLT 5.3 206,000 miles

 

Im having an ongoing issue with exhaust smell in the cab through my AC, especially when sitting in traffic or at a light.  At 122,****** miles, I had my trans replaced through the dealer under partial warranty. A few thousand miles later is when the smell started and I took it back.  They told me one of the exhaust connections they had removed for the swap was leaking and they fixed it.  That lasted about 15-20,000 miles.  It started leaking again but COVID hit and I was not driving as much so I didn't take it back until late last year and at that time they gave me a laundry list of "exhaust issues" that was causing this smell.  Cracked manifold, cracked y pipe, cats needed changed, etc to the tune of $3800. AT that point, I knew I could find a better way so nothing was done. I felt like they didn't know what was wrong with it honestly.  

 

All of that lead to my recent header and ORY pipe install, plus a new tune, but last night while driving it any real distance for the first time, I am still getting an exhaust gas smell through the AC when stopped at a light or what ever. In the past, if I remembered to turn the AC, I would not get the smell and that is how I knew it was coming in through the AC air intake. But summer is here and I will def need AC in Texas. 

 

Ive checked the new pipes and do not see any witness of leaks but I've put less than 150 miles on it at this point.  Has anyone else seen this or had it happen to them?  I can live with it but the family isnt a fan of the smell... 

 

Thanks