well that metal scraping sound is more like a tangy buzz, and im 99% sure that tang is from the flex pipe. comprare under the car your old on vs new, i will garuntee that your new one is half the size of your OEM one. now imagine if you hit the gas and the engine rocks back (accord engines rock like hell) the longer OEM flex pipe will slightly flex and you will have no sound, the shorter one will have to bend alot more to compensate for the lack of length. when it bends more the weaved metal will bind, i do belive this is what makes that metal tang sound, but many have learned to live with it and so can you. i just know that if you are trying to get a nice sound... you are far from it. to prove this, have someone take off down the road while you stand in your drive way... it'll sound like shit. But if money is limited i understand, it will not hurt anything just be mildly annoying.