atvrider4

If you don't want to read the entire story, my main question is at the end...

Alright guys, i finally just went out and bought some ebay headers. i have a 97 lx and to my knowledge, the lx midpipe (front axle to rear axle) is the same as and ex with a test pipe. is that correct? because when i installed the header, my mid pipe was about 1.5" short. and the header flange is like an inch off both up and down as well as side to side. another problem is that the gasket that comes with the header is much too big. so, i just pulled everything tight and bolted it together. took off, and intantly i could hear a rattle. once i got on the road my car sounded decent, until 3k rpms...from roughly 3k to 3500, this obnoxious sound comes from what sounds to be right at the front axle. it sounds like sheet metal vibrating, but distinctly different than the earlier rattle. so, back on the blocks. i diagnosed the first rattle, as my midpipe was pulled so far forward that where it 90s over it was in the heat shield. so, my father and i cut it and put a flex coupler in there. this gave us the extra length and any up and down or side to side we needed. i also installed the correct size gasket, or at least closer to correct. (it fits the header better but a little big for the measley 1.75" midpipe collector) so, fired it up..no rattle! everything sounds smooth! get to the road, hit 3k, and boom, that rediculous sound is still there..what could it be?

From roughly 3k to 3500, it sounds like sheet metal rattling up front, around the front axle. everything is tight, including heat sheilds. What could it be? surely and exhaust leak wouldnt sound like that?