I have been reading all these great posts, but I am still at a loss. I have the stock exaust, dual cats. The cats were gutted sometime ago. I want to put shorty headers on it, which brand will last and is not very loud? I read the some say trash the dual cats for a single, mainly because you can get the proper Y pipes. Is this true? If I convert to a 3 inch pipe with a single cat, how do I re-wire the sensor, or whatever? I assume my car has AIR, and I want the car to be smog legal as well.

So, from what I have read, Hookers seam to be the ones to go with. As far as CAT or 2 CATS, that is straight forward. But what about muffler and any other parts?

I just want a nice smog legal clean flowing exaust, something that will last as well.

Thanks
Hawkeye

 

if u want to keep ur 2 cats try headman 68491. i had same problem with 2 cats and just fabed my y pipe that came with hooker 2055, replaced my cats with 2 catcos. both these headers have A.I.R pips. i think slp has one for 2 cats but i dont the part# but i think there to pricy, i hear hooker has a nice cat back giv them a look.

 

Since you are a newb, now is a good time to get acquainted with the search function. Also, there is a sticky at the top with a lot of great information.

 

omg u SS'er (Say Search).....i wouldnt mind providing some info on his question...


ok, first of all, headers wont give you that big of a sound gain so if you want it quiet, flowmaster and other companies make quiet mufflers.

you will get a bit more performance out of the dual cats, but if theres gonna be fitment issues, i'd say its not worth it and get a single cat. Do you have one or two O2 sensors? Does the AIR tube go into both cats? I put eledbrock Ti-Tech coated headers on my car and they are supposed to never rust. They were 400 bux. These shiny expensive headers u see might not be a good idea because headers can be hard to fit in and u will end up scratching them......and they are expensive as hell.

feel free to ask any more questions

 

Dual cat systems only have one O2 sensor, and the AIR tubes split and go to both cats. I've got DC's myself. Cheapo CATCO's for now. But the exhaust sound is more impacted by the muffler even though the headers and cats also affect it.

I like my dual cats.

 

[QUOTE]Originally posted by DanTheMan_smlk
[B]omg u SS'er (Say Search).....i wouldnt mind providing some info on his question...


Are you going to provide anything new or different from what's already been posted?

 

i did provide info

are you mad about something? I didnt intend to make you angry.

 

Nope, not angry, just wondering what new or different info you provided, that's all.

 

I also have a dual cat 1989 Pontiac. The two 2 1/2 inch cats flow more than a single 3' cat. So for performance keep the dual cats.

I bought the SLP headers for my car and they fit just fine. The Y pipe is after the cats on a dual cat car. The Y pipe is before the cat on a single cat car. The "Y" pipe is not an issue as quite a few are available. I just ordered a Flowmaster "Y" pipe because I'm upgrading my exhaust to a 3 1/2 inch Mufflex system with a 3 1/2 Magnaflow muffler.

The muffler will have a lot to say on how loud your car will be. Having gutted cats will also increase the noise level.

One more thing, here in Southern California those with single cats are converting to dual cats for the performance increase when upgrading their cars. Specifically talking about Dyno Don's shop.

 

As soon as Don breaks free from his current pile of work (or works me in), I'm having a dual cat installed. I hope it's soon, because I can't pass smog until I get those dual cats installed, and I'm running out of time.

 

Thanks guys, I appreciate your input. I have done a search and read some great stuff, spent a couple of hours on this site mainly looking at what folks are doing. I just wanted to hear from other guys like me who want to keep the dual cats. Based on what i am reading here, I can and that makes me happy. I intend to purchase the parts over the winter so I can get it done next spring. I am hoping to post pictures here when I get started on the car. I have done engine rebuilding and even rebuilt a '71 CJ-5 up from the ground. But I have been out of the car thing for some time and I have to get back into working on my Fbird.

Thanks again!
Hawkeye

 

1989GTATransAm,

You are converting to a 3 1/2" system, with dual cats??? Oh do tell, would love to know what parts you are using to do this. Do you have to weld anything or is it a slip fit? Free flowing is the way to go, as well as smog legal for me. Would love to see pics of it when you are done.

Thanks!
Hawkeye

 

Thanks Dan,

I just want to keep the car stock for the most part, and I loved the dual cat thing. Bottom line is I need an exaust and I want headers that will last and sound nice.

Hawkeye

PS - I am sure I will have more questions as time goes on. Thanks!

 

Howdy Hawkeye

Mufflex makes the 3 1/2" or 4" systems for either the single or dual cat cars. I'm having Dyno Don here locally do the installation for me. Theirs is made to hook up to the factory system and therefore necks down to the factory Y-Pipe. To me this is not good. I'm having that part cut off so that it is a full 3 1/2 inch to the Y-Pipe.

The only "trick" part is the Y-Pipe. However Flowmaster makes a neat Y-Pipe that goes from the two 2 1/2" pipes to the 3 1/2" single pipe. Part number is Y250350. So basically it is a slam dunk.

The other good thing is that Magnaflow just came out with a good free flowing muffler in the 3 1/2 inch size and the part number is 12909. Mufflex is now offering this muffer as an alternative. Hope this helps.

 

Keep the dual cats, I have heard that they are kinda rare. I am in the process of getting my 1992 Formula documented through Pontiac Historical Services. I know EVERYTHING that has ever happened to that car, but I want the background info that I'm hoping they can provide. (Did I mention that I special ordered it in the fall 1991, October to be exact) Things like how many of each color, how many with the 5.0 TPI, how many 5 speed cars, how many with the dual converter exhaust, etc.
What you could try, and it is what I am working on, is replacing the manifolds with headers, and then the forward exhaust pipes with mandrel bent pipe. Perhaps even replacing the converters with twin high-flow converters. But you may want to consider keeping the old exhaust, since a new N10 dual exhaust setup is $900 from Year One. That is if you are considering one day trying to sell it for what it may be worth as a collectible.

 

I currently have duel cats on my car but I'm considering converting it to one. Would I be losing alot? Or should I just keep it the way it is?

 

Keep it.

 

There are several thoughts about duals. Some people say that since they are the old "pancake" style that you could replace them with a good high flow aftermarket converter and a good exhaust system, you would actually do better. You might want to consider sticking with a dual converter exhaust, but using some good aftermarket converters, then go with a good exhaust. You could go with a cat-back system only, or could replace the whole system. Personally, what I would do is this: Install a set of good headers. Replace the stock pipe from the headers to the converters, using mandrel bent pipe. (Use 2.25 inch pipe for stock or slightly modified engine, 2.5 inch for more heavily modified engines.) Go with two high flow converters. (Make sure they will maintain emissions so you can pass any testing that is done) Have a good cat-back system installed. (With the muffler, tailpipe and exhaust tips of your choice.)

 

CATS back in the day flowed for crap, nowadays you hardly lose a couple hp. That said I still gut mine. Back when the dual cat setup was offered in what 89 up ? the single cat regular was a bit of a restriction, I believe GM rated the car with 10 more horses with the two cat option.
The way cats flow today one new one will flow as well as two old ones, of course two new ones will flow much better. But on the factory exhaust setup your two cats dump into one tailpipe just as the single cat option did. Unless you are running true dual I wouldn't waste my money on two new cats.

Gut both old cats or,
Convert to single setup with new high flow cat.
Save a lot of clutter underneath and some weight if you just have to have a cat, personally I vote to gut them both.
Always keep in mind that both ways dumped into the same single factory pipe.
Bill E.

 

i dont think you will notice the difference with dual cats and its more expensive

 

I JUST PUT THE EDELBROCK TES SYSTEM ON MY 89 FORMULA WITH DUAL CATS.PART NO.EDL-69723 IT IS THE SINGLE CAT SYSTEM AND I NO PROBLEMS AS FAR AS HOOKING UP THE AIR SYSTEM TO THE SINGLE CAT JUST CUT THE AIR PIPE BEFORE IT SPLITS TO THE DUEL CATS AND BEND TO FIT AND RUN SOME HIGH TEMP HEATER HOSE (I THINK 1/2 INCH SIZE) TO THE CAT AND CLAMP IT. DONE!

 

Hello everyone,

This is my first post on the forum and while I didn't mean to "hi-jack" the thread, it's the closest one that relates to my exhaust situation. (I didn't start a new one for the simple fact of saving a little bit of space. )


I have an 89 Formula with a dual-cat setup. Most of you are probably aware of what it looks like, but I'm all about photos, so here it is (click for larger size):



Here's the stock piping that went to the muffler (had a 5" long rust hole in it):



Here is a photo of the clamp that is used to connect the two pieces:




I REALLY liked the cat-back system (#16829) from Magnaflow, but I can't use it for my car. When I emailed the problem to Magnaflow (along with photos), the reply went like this:

"Good morning,
From what my lead engineer has found we do not have anything that would work with this. We went as far as looking at the actual install photos from the vehicles that we had here to get a look at the stock converter setup and compare to see if any matched your configuration. Please let me know if there is anything that I can do for you. Thank you for contacting Magnaflow."


With that said, what after-market cat-back system can/should I get that will match up with and connect 'easily' to my current two-cat setup? The two key factors is that I don't want to spend a fortune and I'd rather not cut any of the exhaust in the first photo. I searched and searched these forums, but haven't found anything that helps with this particular dilemma. (maybe I just suck at searching - who knows!) I know I can just purchase a replacement section of pipe, but that's my last resort.

If anyone has any hints/tips/suggestions, I'd appreciate all.

Thanks!!!

Mike

 

contact summit racing - they have them. they were oem.

 

Thanks for the response Tony.

I just searched summitracing.com, however, there seems to be yet another dilemma.

While narrowing down the results with this criteria:
(click to enlarge)


I settled on this system from Dynomax (part number 17484):


Okay, so now I'm good to go. The system looks like it will match up perfectly and it even includes a new clamp!

I decided to check the Dynomax site to see if there were any other kits they sold. While looking through their catalog, I discovered that a dual cat setup should actually get part number 17495:


However, when I look at that system's photo on Summit's site, it doesn't look like it'll work with my configuration.

SO, is the Summit site wrong or is the Dynomax site wrong? I have emails into both of them. Hopefully I'll get an answer at which time I'll share the results. In the meantime, does anyone else have any experience with or information on these two particular kits???

 

I have an 89 firebird formula 5.0 5 speed tuned port