I recently went from Thorley TriY headers to Dougs 4 into 1 style. I had previously dialed my Air/Fuel ration on the money with my LM 1 device, using the TriY.

Question: Would just the swap of header styles have any effect on my readings? Both headers have sensors in the collector area. Experts? Did I ask the question correctly?

Don,

I wouldn't expect there to be an extreme difference, but there will likely be some slight difference.

Don, why did you change?

Don, why did you change?

Went to larger exhaust ported heads, my TriY port pattern was hanging over into port too much. Moved up to 1 3/4" port flanges.