Rattle noise on SR20

[Ramonesfreak2010]

So I just finished my SR swap. Everything was smooth. Perfect idle, etc. About a week ago, I noticed a rattle, not a knock. It sounded like it came from the manifold/turbo area. The day before the rattle began, I had installed the nuts on the bolts that hold the downpipe to the turbo elbow. I thought it was the nut tapping on the turbo elbow but I think I'm wrong. Over the past couple days I noticed a few things:

1) It only rattles at idle.
2) If there is not rattle when I turn on the car and I shift at 3000rpm, there will be no rattle at all. Even at idle.
3) If I shift above 3000rpm, the rattle will start.
4) If I don't drive the car for a couple hours, the rattle doesn't sound when I start the car again.

I know its not a lot of info. Tomorrow I will have a sound clip, but hopefully this is enough for someone to figure out. Its a S13 Red top. Thanks.