I have no issue with leaving the cats, in fact I have not removed them from the exhaust yet. I did not go to a dealer for flashing I called a tuner and they only went to oem specs. I am now going to contact the folks that were recommended by you guys. Dave

1941 Chevy
"First rebuild - complete!"
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1941 GMC resting peacefully
1946/1947 Chevy Street rod on s10 frame complete
1945 GMC panel truck in line for restoration
1941 Plymouth stock complete
1941 GMC COE in restoration process
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1941 Chevy Coe uncertain future resting now