When i lay into my car and it reaches about 4 grand on the tach i hear this scraping noise coming from my H-pipe. If i rev it that hight it doesn't do it only when i really lay into it. It sounds as if my exhuast is scratching the road but i know that isn't it that is just what it sounds like. Then my check engine light pops on. Its never done this before and i have no idea what it is. The pipes are still in place just like they were. Any suggestions? Thanks!