truck in my signature 1988 F-150 351W.

Just after the Y in the exhaust system is the first CAT I'm told. Then further downstream is the second one. I thought the first one was actually a resonator, but apparently they are both Cats , is this correct?

Where I live Im subject to emissions. My exhaust is new starting from behind the first cat? back downstream. The original second Cat was replaced with a new hi-flow unit.

So is the first upstream unit a CAT or Resonator ?

If its just a Resonator what effect will it have if I cut that out of the system and replace with exhaust pipe?

If it IS a CAT can it be replaced with the same 3-way hi flow CAT I replaced the other one with?

 

The first one is the pre-heater cat. The second one is the one that does most of the work. I replaced both of them with pipe. The first one was a pain since it was dual in. Look at my gallery. Im gonna order a hi-flow one off ebay soon.

I dont know if you can replace that first one...you gotta look for a dual in cat or something.

 

What makes the first one dual in? is that one with the tube from the EGR.?

 

Actually I found this link.: http://www.car-sound.com/catalog/universal/940.aspx


Since I have annual emissions testing in my area I'm not going to take a chance removing the first one even though it supposedly only reduces emissions at startup phase.. They have the dual in CAT that you mentioned too.