headers

[mstnggtguy02]

hey guys I just installed a set of bassani headers on my 2002 mustang gt on tursday night. Since then when I crank the car up it get to loud thumps from the passanger side, and when I take off in frist gear normal like it feels like its grinding some where, also when I turn the wheel it does the same thing like a grinding. Now I know the steering shaft had to be run through the headers but i checked while I was under there and I didnt see any contact any where. One last thing since I put them on I am getting a mass air meter service engine light code any help on what all this might be? I mean I followed the instructions step by step, and this isnt my frist time putting headers on. Well thanks guys in advance.