exhaust system leak?
 

I've got a leak somewhere. While driving these past two weeks I have noticed an extra hissing that I believe to be unordinary. I have also noticed a light exhaust smell when using my ebpv exhaust brake with the windows open.

I can't find any leaks on the exhaust system, especially since it has all been welded right up to the turbo outlet. I can't find any problems with my oily intercooler boots either.

I'm at a loss and no one else seems to notice it.

Is there anything I have missed in my search for culprits?

have you checked the up pipes they seem to have issues every so often

The up pipes are all welded and I don't see any soot marks anywhere around the welds. I even took a damp cloth and wiped it around the welds to see if I missed something out of eyesight but nothing was there.

the up pipes are welded????