Hey guys, I have searched but havent really found a real answer to this question. I also have some pics to show what im talking about better anyways. So I have three cats, and 4 o2's. There is 1 cat in each down pipe, and 1 last big cat. The o2s are in the down pipes before and after the first cats. There are none right before or right after the last cat. That makes me believe that the last cat is "unmonitered" I guess you could say. Well, what I want to do is possibley remove that last cat, it is a 2 in 1 out, and add a di/do flowmaster. I have already had a flowmaster on this truck once but it wasnt quiet agressive enough for me so I had it taken back out and had a Y put back. I have straight duals Y'ed from the cat back. I was just wondering if I ditched the last cat and had a di/do put on, will I get a check engine light? I really don't see any reason for it since the o2s only seem to be monitering the first cats in the downpipes. Here are some pictures I have taken to show more of what I mean.

Left side first o2


Left side second o2


Right side first o2


Right side second o2


As you can see in the last pic, that is the last o2. Like I said there is 1 o2 before, and after the first cats. There are none right before or after the last one, which is why I don't think it will affect the check engine light by removing it. Im not asking for a lecture on why I should leave it there, I just would like a simple answer to the question. I do plan to leave the other cats there.

Any help is appreicated,
Thanks

 

I got rearended over the weekend and the truck is in the shop getting things taken care of. They called my exhaust shop I always use and got a quote for $350, so they will cut me a check for that and I will go get that done myself after the truck is out of the body shop. That quote is high, all that really needs replaced is the left tailpipe and tip after the Y. I figure they quoted that much for a whole system and the fact it was an insurance company calling. Here is my options.

A. Just get a new left tail pipe and leave them straight
B. Keep the third cat, and get a new left tail pipe but have the Y taken out and a si/do new flowmaster super 44 put in.
C. Take the third cat out, and get a super 40 di/do on.

I really want to try the super 44 because it looks like there isnt much to it in the cutaway on flowmasters site. However, they dont make this in a DI/DO. What do you think? Im thinking I may go with option B. Just want some other opinions.

Thanks,
Mike

 

Have you checked your states vehicle emmissions laws ? In many states it is illegal to tamper with the emission system of which the cat converter is a part of.

 

I didn't care, I was keeping the front two cats. However to make things easier on everyone I think I may just go with option B.

 

yeah, but im not real intrested in that. For one I don't really want a 70 series, and two I like my pipes for the muffler ran up first then back so the muffler is tucked up under the truck. I had a muffler before and thats how they did it. Thanks for the offer though.