i was surfing around found this information.. thought i share and see if anyone has similar experiences or not.
it goes like this.
SILVERTOP MAP CONVERSION
I will explain how I got a good vacuum reading for a MAP sensor on a silvertop 4AGE, but for the rest of the conversion you're on your own. With quad throttle bodies, if you draw vacuum from a single throttle, the vacuum will pulse rapidly making it unusable for a MAP sensor and less than ideal for anything else that uses vacuum like a fuel pressure regulator. You have to draw from all four throttles to get stable vacuum. The solution is a lot simpler than what I was lead to believe. The 20V 4AGE has a "vacuum rail", basically a chamber that is already tapping off of all four throttles for you. It is on top of the throttles between the fuel injectors and connected to the PCV, often beneath part of the engine wiring housed in a plastic cover. It is being used by the AC, power steering, and there is another small line drawing from it I'm not sure for what. The problem with using this vacuum source is that it is being used by the IAC. To overcome this you basically need an air chamber that is larger than one inch inside diameter. I'm not sure how long it needs to be, but I'm assuming it should be at least one inch also. Get a carbuereted fuel filter. One of the clear ones, with fittings about the same size as the AC vacuum line,.. well, that's where I hooked it up anyway. If yours isn't free, get a t-fitting and splice it in there. Leave the element in the filter, it wont hurt anything and it will add an extra layer of protection to your MAP sensor. I got a T fitting and some reducers and connected it to my MAP sensor and fuel pressure regulator. Now the fuel pressure is a stable 37 psi at idle, and I am able to map out my fuel curve with the AEM EMS. I'm willing to bet it will work just fine with a blacktop ECU if that is your plan for the conversion.
COMPRESSION CHECK
When shopping for a 20V 4AGE, check the dry compression. There should be less than 14psi difference between each cylinder, 156 psi minimum pressure, ideally 193 or more.