if you actually have a decent NOS setup, you do get a nice acceleration boost, but it also burns out your engine.
An engine can
be built to take the punishment from NOS, but you're going to spend a mint on head gaskets and piston rings - money that could definitely be better used elsewhere. Generally, you can get away with NOS if you're using it infrequently, and most engines require a full rebuild after less than half a dozen shots.
That said, a co-worker of mine has an engine on the shelf in his home shop that he assembled a few months ago. It runs at ~600HP naturally aspirated, but it's got a wet-fog nitrous system hooked to a 500 shot
for 1100HP. It's built to take the beating, with everything from racing rings to copper head gaskets.
All three movies are crap. You ask why? Because when you drop into 5th from 4th you don't get a sudden acceleration that lets you p00n everyone in the world...
Not if you're going flat out, but if you're cruising at eighty-ish, dropping to fourth will give you a hell of a lot more oomph than staying in fifth. Of course, in straight-track racing, there's never any reason to downshift unless something goes south on you. That move up, move down, hit NOS and win crap from F&F one was bogus, though.
All this is reigniting my itch to replumb the exhaust and intake on my HHR and maybe sneak a PTE turbo under the hood...
Redo the rear end and shocks, new tires, maybe a rear-wheel drive conversion... I want to see a rice racer's face when a retro wagon leaves them in the dust. I'm tired of the world thinking imports rule the aftermarket speed world.
Asus A8N32-SLI - AMD X2 4200+ @ 2.7GHz - 2 x 1GB Corsair PC-3500LL @ 266MHz, 3-3-3-6 - SLI 7800GTs @ 505/1206 - Corsair HX620 PSU - Cooler Master RC-690
The two great evils of system tuning: YMMV and IIRC.