Demon exhaust on a 4 doors Dart?

I agree with adding the 3 inches (or whatever makes it fits well) to the pipes before the mufflers. As far as the flanges are concerned, I'm pretty sure they wont fit. If the donor car has the 340 hi perf exh manifolds they for certain have a different exit on the pass side and Im fairly certain they do on the drivers side. Having said that - whay not take the whole mess to a muffler shop and have them fab the new ends for your manifolds and extend the pipes for your body. As far as the value - you need to judge them from their condition, are they rusty and thin - junk, are they clean and heavy - good. The price is not bad if they are ok, it never hurts to ask for a discount either. While you are at it, get a quote on a whole new system from your muffler shop, you might be surprised or disgusted !!!