thinking of running a test pipe

[BEEVO]

i have a 95 bronco with a y pipe i can tell there is two cats on this y pipe, would there be any problem if i made a 3 inch test pipe and removed the rear cat, that way i can put it back for emissions purposes. does the second cat even make a diffrence also? I'm about to order my exhaust and am trying to decide on this cause if i do im ordering a 3 inch instead of a 2.5inch system. also will a single cener in dual exit flowmaster clear the driveshaft since its a tight squeeze.

 

[BEEVO]

do i even need the second cat? if not im going to run a 3 inch pipe to my 3 inch exhuast

 

[Yardape]

whats your definition of "need"? Will the truck run? Yes it will run, Ford didnt put it there as decoration, it does have a purpose.

 

[BEEVO]

will it run without setting any checking codes i'm not worried about emmissions just wonder since it has a two cat set up a pre and a primary is the second cat the primary needed? thought of taking it out running a 3 inch pipe to a 3 inch 40 series flowmaster.

 

[BEEVO]

any opinions of this please give comments i ordered a 2.5 inch 40 series so i'm planning rinning a 2.5 inch pipe in place of the 2nd cat would this cause any check engine lights. i also heard in most state the pre cat thats first passes most emissions anyways.

 

[Broncobill78]

I can't say that I have any direct experience with this but I really wouldn't expect it to pass inspection without both of them & it surely won't pass a visual. Just how important that is to you I don't know. The 2nd cat isn't there because Ford wanted to do it's part to help keep up the global demand for platinum, it's there because that's what it takes to bring the emissions down to what regulations require. Now maybe you can still pass inspection by tuning it or running the A/C during inspections but that'll be a hit-or-miss kinda thing. If *I* lived in a state that was really **** about stuff like that (speaking as a former Massachusetts resident) I wouldn't do it but not all states get worked up over vehicle inspection stuff so it's a judgment call. Personally I'd install a 49-state cat-back system and be done with it. You won't see any performance gain by removing the cat and you might run into nothing but headaches with the whole inspection process.

 

[Bronc76]

I think if you live in a state that has inspections, whatever the vehicle came with from factory has to be on there, if you take them off i wouldnt throw them away.

 

[bobstrat]

if i'm not mistaken (and i could be mistaken) they are designed to work in conjunction with each other. one is sort of like a preheater or something.

maybe you'd be better off with a hi flow cat and ditch both originals.

 

[Broncobill78]

Yes, the main converter needs to reach a certain temperature and "light-off" before it begins to work efficiently. The converter closest to the exhaust manifold is a pre-converter which works much more efficiently at lower temps and is there to reduce emissions while the primary comes up to temp.