You could build a lawn mower that could beat a chrysler ME412 also, but you are sacrificing a lot of things. Building a civic that can beat a viper for 14 grand maybe nice, but you will have crap reliability from the poor engineering of the aftermarket mods. You will also probably sacrifice fuel mileage (yes even worse than the viper) since the engine will be tuned up to its max. Also when you break the 2Hp/CI barrier on an engine its life expectancy drops a lot (unless engine is forged well), its like making a person faster by doing steroids. But then again you only paid 14 grand, its kind of disposable, just build a new one every year. In the long run it will end up costing you the same as a viper since you'll have to keep rebuilding the engine when it explodes.
Now my V6 mustang would be a challenge to beat the NSX in the quarter mile, and probably impossible in a track race since it is way out handled and is too heavy, but it is possible and would be cheaper than a NSX yet still look as good and in my oppinion better.
Oh and 05 Mustang is SICK and the new special edition ones have 5.4 Litre 400- 500 HP engines in them for only 40-50 grand when they come out. So if it were up to me, i'd rather havea C6 Corvette, or a new Mustang Cobra equivlant (dont know what they are calling it) and an old used WRX for winter AWD BABY!