[Double Venom]

werntonb,
I think Cobraman's leak is coming where the four tubes come together at the flange. It IS impossible to get into this area "from the outside". Even a #2 Mig gun is way to large, but...

Pull the sidepipes-headers apart and weld to the Inside as "redmnt" suggested. #1 with an external Bright light aimed at the "suspect point" you should be able to actually see hole/gap in the original weld points from the inside. #2 Now it is A fairly simple job to clean the inside joint(s) and re-weld without burning through or ruining the outside finish.

Cobraman, by the time you waste your time trying to clean up the guilty area, try and shove the ol' JB into it, "it" fails and you do the above all over again, pull it apart and weld from the inside. Job done and permanently this time.

Yours isn't the first with this problem!

DV