Been there, done that. If I could give you my .02, it's not worth it. We realized absolutely no gains switching from manifolds to headers. As a matter of fact, we encountered problems with the O2's on everyone I've seen. The O2 sensor placement (or lack thereof) is placed in a poor spot on the MSDS and Weapon R which does not allow the full flow of all 3 cylinders across it (only 1 cylinder). This causes low speed richness concerns and cold starting problems. I experienced it, others have and we've all ditched ours and sold them.
This is my word, it should be taken as an opinion from someone who has gone through the installation and ran it on a 3.0L. I've been party to a 2.5L Cougar installation as well and the same issues were present on it as well. I myself wouldn't recommend it.
Is the info i got. I'm just trying to get as much info as possible so please keep it nice
