Nitrous is safe as houses as long as it's set up right...

By that i mean using Wide Open Throttle sensor (WOT) and a window switch which means the gas is only active between certain rpm's.

i.e 3000-6500 etc.

If you bring it in too early there's a risk of bending rods...

Also - have it set up on a rolling road with the use of a wideband lambda sensor - the way i used to do it was to braze the jets with a blowtorch and flood them with solder - then drill them out at 0.1mm intervals until it made good power under safe fuelling...

If i went too far, not a problem, back it off and then refill and redrill...

All this '50bhp shot' and '75bhp shot' stuff is absolute bollocks - i've never yet found a kit that safely makes the 'listed' power straigh away, its normally a lot under...

As with anything - if you do it, do it properly and it won't fuck you over