I am using the one from Nitrous Express.. it's only like $36, and I believe it comes set at either 30 or 35 psi.. but you can adjust it. The only problem adjusting it you need a gauge of some sort to measure what it is set at..
I'm useing the NOS Fuel Safety Switch (part # 15685) . Ordered it through Summit $34.00
It can be adjusted from 25 to 50 Psi and is very easy to install. All you need is a 12 volt Dc test light. On your car I believe you want it set at 35 psi
If you want email me at [email protected] and later I'll send you a copy of the instructions, so you can check them out.