Doug Thorley Headers

What in addition to the headers and a flowmaster cat back exhaust do I need to bring to the muffler shop? How many and what kind of high flow catalytic converters do I need?

 

02 simulator so ur dont throw a CEL code

 

and for your cats, ur gonna get rid of the 1st set with ur long tubes, youll still have the 2 reat cats in the stock y-pipe that u should just leave alone unless u like the sound of just stupid loud then get rid of all 4 cats

 

Sorry for the simple question but will our trucks pass emissions with only one set of cats?

 

Does the o2 sensor have to be eliminated? And currently its setup with the cats on the ends of both manifolds, the whole system is gona be attached to a flowmaster cat back system, where should the new cats be positioned? When the headers come off the engine it should be going into a single pipe should it not? And arent the doug thorley headers shortys only?

 

k ur headers are gonna connect to a y-pipe, then ur y-pipe is what is gonna connect to ur flowmaster cat back system, ur still gonna have ur stock y-pipe which has the 2 rear cats.... the 02 simulator is some wiring so u dont get an CEL. u dont have to install it, but its a good idea to

 

depends what ur emissions are like. if they sniff then ur not gonna pass with no cats. if they visual then u can get away with it if u have ur rear cats or the pipe bomb with resonators that kinda look like cats

 

The headers come with o2 sensor hole. So wouldn't I just have to put my stock sensor in the header?

 

Thanks for the reply, under a sniff test, will it pass with only the rear cats? Prob not?

 

probably not. ur first pair of cats do most of all the work anyways. youll have a better chance passing with only front cats compared to only havin rear cats. i still have my front but canceled out my rear. but before emissions ill just put the stock y-pipe back on to pass the sniff, shouldn take long.

 

i think u might be a little confused, read this, itll make better sense

http://www.urdusa.com/product_info.php?cPath=66_72&products_id=1260518515

 

Im trying to get an idea of how to lay this out because the muffler shop cant spend time finding parts to install. The current exhaust manifolds come off of the engine and right down into cats, now the doug thorley headers look like this...



and the stock manifold with cats look like this, and on both sides im seeing cats coming off the manifold, then connect to the y pipe, my question is what do i need to replace these with in terms of high flow cats, and will any other pipes be required?

 

oh ok so your gettin the short tubes?!?!?!?! thats gonna cost more to install cuz ur gonna have to take out the header, weld to cat, then put back on, then back off, then back on. i thought u were gettin the long tubes which is easier of an install. with ur set up u will still have all 4 cats. make sure the shop is a reputable one cuz if they mess up on the weld u can have some crappy leaks

 

and u do not need high flow cats, not worth the money nor the labor

 

I know that I will have all 4 cats, I'm asking what kind I am going to need?

 

ur still gonna use your stock cats. just show up to the muffler shop with everything in the box and ur fine. i think the dt shorties used the regular gasket so u dont need to get that one.

 

Assuming i wanted to replaced the cats, or had to, im just concerned about the length of the cat and passing emissions, thats what im unsure of. I can get two catco universal cats for 30 each thats not a problem, the problem is what is the correct length of the cat so that it does pass emissions.

 

dude save your money!! the headers are made specifically for you to weld the stock cats to them so u dont have to worry about the length. u will still have all 4 cats so u will pass emissions!! dont worry!

 

well there isnt 4 cats on there now anyway, only two, here let me show you how its setup...



this is judging strictly by what i can see under the car, now the muffler shop will use the existing cats but the price could be raised due to the fact that it requires more work to cut them off and fix the ends for welding given the fact that they are rusted up so bad, im not so much concerned about the money factor if it involves it being done the right way so it can last, i dont want the shop to try to weld on a rusted cat and it start leaking a few days later.

In addition to the headers being installed i also have the flowmaster cat back exhaust which is shown here...

 

k ur not makin any sense, im sorry. all of our trucks have 4 cats. two connected to ur manifold, then two are on ur y-pipe. ur drawing is missing a set. unless u have an aftermarket y-pipe that u didnt tell us about . go under truck and take a pic if u can