I paid $180 for my extender and I love it. It really woke my car up. For the money, it was by far the best upgrade I have done to my car so far. There are people out there that are running them with turbo and superchargers. I guess it boils down to how much time, money and effort you want to invest. The tweecer has been discussed many times in these forums and the worst thing I have heard about it is the diffuculity for some people to program it, while some people have no problem at all so this is a user issue , not a product issue. I don't think you can go wrong either way. There are usually some of both on Ebay. Just remember that the 94-95 uses a specific extender and they are usually cheaper than the 86-93.
That is not the way it works at all. It doesn't trick anything, it comes in at 2500 rpm and takes the computer over with revised timing , fuel, rpm etc... tables. Go to the corral and do a search on it and you will find some really good info. If money and time are not a factor, then by all means go with the tweecer.
the one thing the tweecer is worth the money for is the fan control. Let alone everything else it can do. It was/is hard for me to learn but with the help of a program called eec analyzer you can probably do it.