I still need to call you about a nitrous set up for my racecar. I am going to be building another 455 sometime (This winter hopefully) with a girdle, and maybe a half fill. Thinking turbocharged with a shot of nitrous.
Turbo......with a small shot? Now your talking my language. I would love to talk to you about that setup. Working on one myself. No reason a 455 can't make big streetable HP with a properly built setup.
Nitrous is GREAT with a turbo- not only will you spool up faster, but the nitrous will act as an intercooler. Just watch that fuel delivery, especially while building boost. And don't run too rich the rest of the time, just to compensate for that lean period when you build boost... (That's probably more controllable with a supercharger, unless you run computerized FI) -BC
And don't forget to put a good inline filter between the Bottle and solenoid. Most NOS bottles (overhere at least) are beed blasted on the inside for cleanup with little metal balls. (medical NOS bottles are cleaned another way and don't have this problem) They can't get them all out so if you don't run a filter to catch the metal balls coming out of the bottle. The magnetic solenoid will catch them and keep the solenoid open and it will not close anymore. Have seen engines burning up for that reason downhere.
I have only used N.O.S. brand systems. 150 to 200 hp on a 455 ci engine is not that much because of cylinder volume. Buy a new system unless you know the person and saw the system work. Start out with 2* retard per 50 hp of nitrous and start out 2 steps colder plug, 950 bottle pressure. Most importantly read instructions, which no one ever does. Read the plugs and see what it wants. If you are a little nervous call this guy and he will set up and sell you a working system from the start. Take it out of the box read his instructions and look for your goal appliednitroustechnology.com Jeff Prock, if you call tell him Todd Scribner sent you.