help pls 04 sti decat down pipe
 

hi can any one give me infomation on down pipes and sport 100 cell if i fit any 1 of these pipes will my light come on i mean my managment light on dash if so where could i buy a anti foul kit thanks very much will these pipes give me much bhp is it worth it or should i not bother my car is stander appert from dump valve and prodrive back box i am thinking ov panel filter and fuel pump thanks lads