installing Fuel pressure regulator!!

It's easiest to get to the screws on the underside if you pull the upper intake off; really easy if you pull the fuel rail. If you decide to do that, you'll need the fuel line disconnect tool. If your egr spacer is still there and hooked up like stock, you'll need to block off those coolant lines to keep them from leaking when you remove the upper. And you'd probably be wise to have several feet of the proper size vacuum hose on hand because many times it's easier to simply cut them off and replace them with new vacuum line. ESPECIALLY if it's original vacuum line - screwing around with the old brittle lines frequently results in vacuum leaks. Good time to refresh/renew your pcv system - screen/grommet/valve/hose - all easy to get to with the upper off.

Not sure how to break this to you - but you won't be seeing any lasting performance improvement from an adjustable pressure regulator - unless your stock unit has malfunctioned. The system is designed to operate best at the stock pressure - 38-40 psi measured with the engine at warm idle and with the vacuum hose disconnected from the regulator and plugged. That's where you should set the new one at and leave it alone. You can temporarily effect mixture by raising/lowering, but the once in closed loop, the computer will effectively cancel out your changes. It's gonna look at the O2 sensors, and adjust mixture back where it wants it by changing the pulse width of the injectors as they cycle. So if you increase pressure to richen the mixture past where the computer wants it, it will simply shorten the amount of time the injector is cycled open. Once you've driven the car for a bit, the computer will effectively un-do your pressure change for you.

At wide open throttle it ignores the O2 sensors, however, over time the computer will also make adjustments to the w.o.t. tables to affect change there too. So I wouldn't do anything but set it at the stock pressure.

The only time running at a higher pressure may help in a sustainable fashion is if you're running way too small an injector for your HP level, and using increased pressure to make a smaller injector act like a bigger injector. But even then, it's not the best way to solve the problem; and you're not in that situation.

Good luck with the install.

heres the idiots guide to install one....with pics http://www.cardomain.com/memberpage/461740/4

I've installed air filters that were harder to do than a 5.0 fuel pressure regulator. I wouldn't expect any noticable gains on an otherwise stock engine.