Here are my car specs:

91 GTA with 5.0 TPI "F" engine with 100K miles. Engine and exhaust are all stock. Label under hood for Catalyst info reads: AIR/EGR/TWC+OC/02S.

A few questions I have are:

1) If that is the original cat, is it possible it is still functioning and efficient? (Car passed emmissions 2 years ago. But 1st test failed emmissions, then I did a full tune up and 2nd time it passed. Inspection is coming up again.)

2) The rear pipe and muffler are rotted and must be replaced. Would it be worth it just to replace the cat at the same time to be on the safe side?

3) I plan on keeping the stock manifolds. Would there be any benefit of going larger than a 2.5 system (if even possible)?

4) And I assume stick with a mandrel bent system?

5) Is the stock system a 2.25" or 2.50"? Do you measure it by the outside of the pipe?

Pricewise I am not looking to spend alot for a top end system since I don't think I would be able to take advantage of that considering my engine is stock and only produces 205 factory horsepower. Of course I am looking to increase performance if at all possible with what I got. I just don't want to buy crap either...something decent and good quality for the money. Something not really loud with a low, mean-sounding exhaust note.

Any suggestions, recommendations, and opinions would be greatly appreciated!!

Thanks,
Rob

 

check out summit or jegs. mayb try dynomax super turbo exhaust systems, ive never had them but for the price u cant beatem. they run about $170 or so and u will get some power gains.

 

I have a 91 TPI 5.0 5 speed with a few miles...

I ordered a new Magnaflow 3 inch Cat (which flows better than stock) & a Flowmaster Super 40 (the black one) for my car as well...

I ordered both from a guy on Ebay (that sells exhaust stuff)... After I get my headers installed, I can take those parts to a muffler shop and they said for about $200 they can provide / bend / weld all the pipes to connect it.

Here is an ebay link, he sells a lot of stuff...

http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWA%3AIT

 

I just bought hooker super comp Long Tubes with hooker catback. Ran me a total around $600. Only problem is that I need to find a Y-Pipe.

WOOT 400 posts!

 

Not many responses. But thanks for those that did respond!

I have done some research on these boards on cat-back systems. I am favoring the Hooker cat-back. I have read many good reviews on it. Also most people said that under idle and cruising rpm's it really isn't that loud which is what I am looking for. But it still has the deep, throaty roar to it as well under heavy acceleration which is nice.

Now to find a cat to mate with my stock manifolds. I was comparing prices and it seems $100 is average so I wouldn't want to go much more than that. I definitely want a direct-fit unit. From my research it seems most people favor either Catco or MagnaFlow/CarSound. I read the specs on CarSound's website and they sound like they are really good quality cats, however I read a few bad opinions on these boards regarding them. My main interest is getting a quality unit...with performance & sound a close 2nd. It seems Catco is very popular and recommended a lot.

Opinions from people that have experience with these brands..... Overall would you say they are both good quality or is Catco still a notch above in terms of quality, performance, etc? Thanks again.

 

Your car has the small, restrictive single cat system (sized by the pipe OD, for what that's worth). Finding a system to fit the stock manifolds isn't the issue, since you aren't doing anything to the stock, restrictive y-pipe. Since you aren't doing anything about that, it doesn't make much sense to spend the extra money on a new cat. If you're passing the sniffer check, there's nothing wrong with it. Replacing it with a high flow type isn't going to make much difference, performance-wise.

There's another thread started about the same time as yours about someone who ordered a cat back from Jegs. It isn't the right system. Make sure wherever you get the system that they know that you have a '91, and that they know it is not the same as a '90 or earlier. A proper system for a '91 may have a larger pipe than stock, most likely 3", even though it will fit your smaller cat outlet. It will help a little compared to the stock system, but the real restrictions will remain unless you replace the y-pipe. The right way to replace the y-pipe would be with emissions-legal headers for the '86-'90 TPI single cat application, which will have a y-pipe with a 3" outlet (the Hooker 2055's probably being the best choice there), and getting cat and cat back for the same application.

 

I have a 92 Formula305 F coded motor.
#1 It is entirely possible that the cats are working just fine. Had to get my car smogged last year, and it passed first time, no problem. I just made sure that I drove it enough to make sure any old gas was used up, and then went for a ride to make sure it was up to temp. before taking it in.
#2 Laborwise, it makes sense, but I don't know how much a decent converter costs. Your call.
#3 I don't know about any benefits, but I don't think it would hurt anything.
#4 Mandrel bent is preferable, but it may be somewhat hard to find. Especially if you are not going to replace everything all at one time.
#5 The pipes from the front of the dual cats on mine are 2.25", while the intermediate pipe back to the muffler is 3", and the dual tailpipes are 2.5". What I did last year is replace the original muffler, (I ordered the car new, so I know for sure it was the original), with a Flowmaster Series 80. There are two 3" inlet with dual 2.5" outlet mufflers. The major difference is that one of the is 5 inches thick instead of 4 inches. That is the one I used and I like the exhaust sound just fine. I also kept the stock turned down tailpipes, so it isn't as nasty a sound as some I've heard. Most people might not even notice the difference, but there is a difference.

You might try going to some carshows, and looking and asking around. Someone will probably fire up there Firebird or Camaro if you ask. That way you can listen to what they have and see if you like it.

 

Well if you fail emissions, you should def. get a new exhaust. I would go with a new catco cat and a catback of your choice. If you're already taking the rest of the exhaust off, you might as well do the headers also. For a FULL exhaust system. (headers with smog equip, new y pipe, cat, catback, muffler tips) It will cost about 800 bucks installed. This combo should give you 30 rwp also.

 

Your factory cat has two "beds" of the ceramic/platnum material, somewhat restrictive but probably work for a long time yet. An aftermarket converter has one bed, less restriction and more sound, still does the job it seems. I'd go with a Catco direct fit converter, a Dynomax Super Turbo cat back exhaust kit. Best deal for the money, sound really nice, and well made good fitting parts that will last a long time. Get the parts made for your exact application.

 

If you are looking for a low buck system, you could try and pick up a used 4th gen cat back. They are 2 3/4" mandrel bent and stainless steel. They will need to modified in order to work, but any exhaust shop should be able to do it. You can usually pick one up pretty cheap as well.

 

Stainless steel? Man, I turned down a fourth gen exhaust system for free, if only I knew. Now I do anyway.

 

It would still be the small diameter, so the difference would hardly be noticeable.

 

Thanks for all the suggestions! I did look into a couple of them.

After seeing the cost of the Dynomax Super Turbo cat-back I was interested and thought I would research that option. They seem like nice systems, but many people said they are pretty quiet and don't sound much different than a stock exhaust. I am not looking for loud by no means, but I would like to hear a little something. The other thing that turned me off is that it looks too much like stock without the pipes exiting the rear as most aftermarket exhausts do. I think it gives the car a mean sporty look with them out the back just a bit.

With that being said, I am favoring the Hooker Super Competition cat-back system. From what I read it has a nice deep rumble but isn't really that loud at idle and cruising speeds. The model of it is #16822. I understand that this is $50 cheaper than the #16823 which is actually called for on my car but the only difference is the connection of the I-pipe to the cat. The 16822 has the flange to bolt them together.

I am considering replacing the cat as well while I am doing the job just to be on the safe side. I know that going with a high-flow cat won't make much of a performance improvement without ditching the restrictive stock manifolds and y-pipe, but it's gotta be better than stock and at least I'll know it's new. If I go to NAPA and get one who knows what the quality of it will be and it would probably be a universal fit model which I don't want.

Question:
Let's say for instance I get the Catco #4115 cat. It has a flange 2.5" outlet diameter. The Hooker 16822 has a 3" I-pipe diameter and also with a flange connection (from what everyone is saying). Even though there is a difference in size, are they designed to bolt up together or is there some kind of a conversion adapter I will need?

Any help would be much appreciated. Thanks in advance!

-Rob