That is correct in essence. To eliminate the thermo reactors you would also need to disconnect the air injection and the EGR, neither of which is a big deal but they do feed into the thermo reactors. A cheaper alternative to headers is the basic cast iron exhaust manifolds off a Bavaria or the post reactor cars going as late as the 88 535i. The later ones have slightly bigger passages but not enough to worry about bothering with in my opinion. Mike W.