I guess there's a difference between what I "think" and actual advice about Missouri law.
What I think, the vast majority of this emissions testing is a joke. Like most government programs, it started out as a great idea -- originally it was determined that the smog in southern California could be reduced if a PCV valve was installed in place of a crankcase breather on all new car motors. It worked. Then it was determined that emissions could be further reduced with an exhaust gas recirculation system; helped a little more. So the government soon went wild with all manner of mandates, to the point of new cars requiring twice the engine with half the horsepower, and then the automakers were lambasted for selling gas guzzlers! Don't get me started!
There was/is a plan which specified that all cars registered in certain metropolitan cities and surrounding counties be tested for emissions, for the purpose of keeping air quality under control in dense areas. I did this, back when I lived in the DC area. However when I moved to Sarasota 25 years ago this was long forgotten -- so I personally could care less about the progress of this, or how much of it still exists.
I DO remember however that the law, at least in Virginia, had provisions that exempted cars 20 years and older, and also allowed for an exemption if the estimate for repair was to exceed a certain amount. Vehicles built in model years 1965 and older (and actually 1966, for places other than California) did not have these clean-air mods from the factory and were exempt from requiring tests. The whole purpose of the testing anyway was not to force a small handful of collector cars off the road, or older, well-maintained vehicles, but to reduce pollution by ensuring the masses of commuters and grocery-getters are meeting the standards they were built to adhere to.
With this in mind, it might be wise to re-read the Missouri law. I don't know what it says, but it's probable that a 1990 or older vehicle may have an exemption of some sort, or there may be a limitation to the amount paid to bring it to standard. Unfortunately for us gearheads, modifications to modern engines are often strictly limited due to the emissions standards. Just one more reason why older vehicles, typically 1965 and older, are better suited for street rod material.
As for purchase of a 1990's car, the question certainly arises of whether this car will pass emissions tests to begin with. If you fear it can't because of mods, or engine wear, find out ahead of time what your level of responsibility is before buying. Get the whole story, then go shopping with that in mind. Don't overlook the fact that repair expense could even be used as a bargaining tool!
