...need to use? Long story here, nephew messed car up while trying to "fix" it. I need to make emission compliant and soon. Needs whole exhaust replaced from engine back plus sensors and the such. I found universal converters that fit but was told I need one with 4 openings not 1 at engine? I have no idea of any of this and the mechanic is giving me a lot of BS. I hope someone can actually tell me what I need.