I modified the factory FPR. As for the moaning, I figured out that it was being caused by unforseen circumstances.
I tapped out the vacuum port on the fpr to accept an 8-32 screw. Then I used it to apply pressure to the piston that closes of the fuel port on the regulator. Worked good at first, but when the car got hot I had the moaning issue.
1st, if the screw is too high, then the manifold will touch and push down on the regulator. The metal will flex so you can get it on, but closes off the valve and then the pressure jumps to about 80 psi. Fixing that allows easy adjustments except for one more issue.
When the car was cold and I adjusted the screw, I could get the exact pressure I needed. That was fine, then I would button it up and drive it. Soon it would start moaning again, and the pressure was up to 80 psi again. The chamber was not vented (because the screw was blocking it) so the trapped air expanded and applied way more pressure. I solved this by grooving the screw with a dremel on one side. Then you can use a small nut threaded up the screw close to the top to lock down the screw to the right adjustment.
The only problem with this setup is that the pressure is fixed, and the pcm needs to have a pressure jump when you hit full throttle. It seems to work fine to keep it from being too lean at WOT though.
I don't think there are many aftermarket FPR's that will fit in the location. I only had 1/4" to play with above the stock fpr.
You will have to find someone that actually got an aftermarket to fit. Obviously I'm too cheap to spend money on something I can modify myself.
wamonger
good luck.
