Go with Nos
If you only have 700 get a Zex or Nitrous Express kit. That will take a sec or two off your time with money left over. Its not bad for the engine and you can still upgrade with other parts. The only thing that you don't want to do is run anything thats going to advance the timing. With Zex you can get an extra 75hrs. More bang for the buck.
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" Nitrous is like a hot chick with an STD, you wanna hit it, but you know what the consequences might be "