well, a few weeks ago, i started noticing this really wEird, high-pitched rattling/whistling during cold start. after the car would warm up, it would go away, though. and also, like, if i let the car bog a little, the same rattling noise comes up again. wat is it? i think it's coming from my headers or somewhere in my exhaust system, so ya...? can anyone help diagnose this? any help at all is appreciated! thanks!