if youre paying for a nitrous kit, you might as well pay for one that sprays INTO the intake charge instead of just ON it. I don't know how much those sprayers cost, but its hard to imagine it being worth it.

If youre trying to get the most out of a stock setup, you might look into water injection. It lowers the intake temperature a bit, but more importantly, it slows the burning rate, giving you smother, more controlled combustion. That ads a major safety margin if youre running higher boost than you feel comfortable with.

I know this route isn't very popular with the honda folk, and I'm not quite sure why (let me know if you do), but my roomie has water injection on his car, runs nearly (occationally over) double the stock boost pressure (up to 23 psi, occational 2 bar spikes), has hack-job management and we don't have very good gas here. When we took off the head to do his head swap, everything was in perfect condition, no pitting or scarring that would indicate hotspots or dangerous a/f mixtures. I credit this partially to the stoutness of the saab motor, but also to the extra tuning cushion water injection gave us.

JMO