Calling all Guru's - peculiar noise after injector swap

[93GTDIN]

As I've become impatient waiting for my intercooler to arrive on my procharger, I decided to get a head start on things and throw on my 30 # injectors and new Granatelli MAF.

Before the new injectors, sometimes I would get what I can only describe as a "spurting" sound under light accelleration. It wasnt that bad and didnt happen all the time. The noise was and still seems to be:

* Independent of engine speed, IE the noise doesnt cycle faster as engine speed increases
* Only happening under light-moderate accelleration
* Sound makes a bell curve:
- IE:
1K - 1.5 K You cant hear it
2K - 3K Becomes noticable
3K - 3.5 K Becomes very obnoxious
4 K -> 6K goes away completely

I kind of figured my injectors were dirty cause they are 44K miles old, and when I pulled them out they looked like crap, and that was what caused the noise. Actually it got much louder and meaner sounding with the new injectors. I thought I had it figured out earlier today when I noticed my radiator was bone dry, and the noise was the water pump trying to pull fluid out of a nearly empty radiator. I filled it up and the damn noise is still there.

Does anybody know what this noise is?