2002 Express Van 5.7 Dual Exhaust to Single Exhaust.

[Themerlen]

Incorrect, 3 upstreams on the factory single cat trucks. It very much does change how the engine runs.

GM has factory Express van tunes for L31s with a single cat as well as no cats and even no 02s at all. Some of the L31 calibrations are open loop only even.

Tunercats has the option to directly edit the Dual vs Single cat exhaust configuration, I made a dual cat 305 calibration when I put the L30 into my Tahoe and also made a single cat L31 calibration when I put a Mercruiser version of the HT383E into a 2005 Astro.

This would be the setup that I have. You wouldn't still happen to have a .bin file for an single cat L31 you'd be willing share, or know where to find one. All the ones I've found so far are dual cat. But now that I know it exists, it might make it easier to find.