If you're going to put nitrous on your car, especially 100 shot or higher, spend the money and do it right the first time, or you will be spending the extra money to fix/replace a motor.
$700 won't even cover the cost of something that adjusts timing and the tune to use it, a UTEC. The tune itself will run you around $400 by a good tuner.
I built my 150hp shot Z back in 2008, and it's still running strong. But I spent the extra on all the safety items and proffesional tune. You'll be into it at least 1200-1500 if done right.
2006 Touring with A/T - Altered Atmosphere Angled Plenum Spacer, UTEC w/proffesional tune, Short-ram intake, HiFlow Cats, ZEX 150hp shot with ALL the safety bells and whistles - On Bottle - 339whp / 372wtq. NA with UTEC tune - 248whp / 223wtq / Stock - 213whp.