The MAC long tubes should have the sensor bungs welded into the collectors. Is that the case? If so, I think they are close enough to the original location that they shouldn't give you too much of an issue. You may get momentary rough idle upon initial start up or maybe a little longer period of rough idle when it is really cold, but you shouldn't need a tune for your combination just because you put headers on.
Heated sensors will not generate enough heat to compensate in open-loop mode if this is truly a lack of heat in your exhaust issue. Further, your sensors are heated - if you doubt it, unscrew one, let it hang, turn the ignition to run, and touch it. It will be hot.
The key is that you want your o2 sensors about 15-16 inches or so from the head. This is due not only to the heat issue but also the table in the EEC that controls when they sample. Not only do they need to be the correct temp, they also need to be looking at the exhaust at the proper time. Distance away from the head can affect both things.
If you don't have ceramic headers, try wrapping them...?
Heated sensors will not generate enough heat to compensate in open-loop mode if this is truly a lack of heat in your exhaust issue. Further, your sensors are heated - if you doubt it, unscrew one, let it hang, turn the ignition to run, and touch it. It will be hot.
The key is that you want your o2 sensors about 15-16 inches or so from the head. This is due not only to the heat issue but also the table in the EEC that controls when they sample. Not only do they need to be the correct temp, they also need to be looking at the exhaust at the proper time. Distance away from the head can affect both things.
If you don't have ceramic headers, try wrapping them...?
