71nova

I have a 1990 IROC 5.7 G92 original including exhaust no mods. Do you gain anything performance wise from adding a cat back system and not changing anything else? How much of a difference will a cat back exhaust upgrade make in the way the car sounds without changing anything else? The car is very quiet with the stock exhaust and I could appreciate a more aggressive tone. Is it worth the money to add a cat back? Is the original exhaust system something I should hang onto if I decide to change it?

rarebmx

iTrader: (6)

The G92 also gave you the N10 (dual Cats) so that added something between 12 - 13% more HP. I canot answer the advantages of adding catback - I am also wondering -
I would save the oriignal exhaust if possible.

paul_huryk

The factory exhaust will have non-mandrel bent tubes and a restrictive muffler, an aftermarket exhaust should add power. The only thing the dual cat system gives is a better y-pipe and freer flowing cats.

1985WS6TA

The stock mufflers were pretty restrictive so it definitely an upgrade to do any cat back system. If you want to save a coin, you can get just a muffler that fits directly in the stock location which is still an improvement over the stock muffler.

85FBTranam

iTrader: (3)

Most cat back systems are mandrel bent, which should offer up some very minor HP gains...if nothing else in the world it will sound better

You probably won't want to swap back to stock, but hang onto the parts if they are in good shape.

71nova

Thanks for the input. I'll probably stick with the stock exhaust for a little while longer. I have more important issues like paint for now. It looks like I would have to cut the pipe that goes over the rear axle to get it off. Is this true? Was the rear installed after the exhaust originally at the factory? I tried to just unbolt it before and could not get it.

1985WS6TA

Yes the exhaust was installed first and then the entire drivetrain was raised up into the car in the factory.

85FBTranam

iTrader: (3)

May be able to snake it over the rear axle with a cut at the muffler, but would need the car in the air to have room to swing the intermediate pipe.

87Proud

I did a Magnaflow Cat back system that they said gave 10% or more in HP increase and the car sounds mean. And I love the exhaust so much I even did a Magnaflow performance cat. When I first did just the cat back I could feel the difference. It wasn't like "WOW!" But it was still noticable to nod your head and go "oo not bad." As for sound its nice and quiet at cruise speed but when you give it gas you'll hear it. And the Magna cat just even added to the sound and made it even better. All I need now are some headers ha. I'm pretty bias when it comes to exhaust and I say its all about Magnaflow.

BruceEmbry

Hi,
I'm in the process of restoring my exhuat system to OEM style. I am going with the dual cat convertor assembly from catco and Quiet-Flow 3 muffler from Walker. All of the pipes will be mandrel bent. I have ordered all of the parts through Summit Racing.

After replacing my orgial 305 LG4 with a 350 Tune Port, using a new high flow cat the new 350 would easily wind pass 5000 RPM. After lthe the SLP cat-back the engine felt strouger and louder, but would not wine to 5000 RPM as fast as it did with just the with the high Cat and the orginal 2.5 inch exhust system.

Well I have gotten tried of the loudness of the exhust system.

I just received the new Walker Quet Flow Muffler today. The muffler looks very nice. I just have to wait for the rest of the exhust system to come in.

83 Crossfire TA

iTrader: (2)

I would argue that most of that "not bad" reaction comes from the different sound. I know that the early 3rd gens actually had a better sounding exhaust, but it didn't flow great, but then with the 4th gens it got pretty decent flowing. On my '97 WS6 I've run it with and without the stock muffler and wasn't able to document any change in performance at the track, at all. And I'm not sure that the late 3rd gen is any worse.

For a stock car I'd be pretty surprised if you really saw a difference unless you installed headers, and then the muffler would be a bigger restriction than the pipes (I've run 11's through he stock 2.75" intermediate pipe), followed by the cats.

VincentZ28

iTrader: (2)

If you add a Flowmaster Y-pipe after the dual cats, then a 3in cat-back the air flow would be even better. The stock Y-pipe is restrictive. I replaced my entire exhaust system with dual cats an the wheel horse power increase to 255 with tune when the car was stock and the bottom air filter cut out.

BruceEmbry

Hi,
I don't have the stock Y-pipe. I have the SLP -Ypipe, two pipes, one from each side of the engine. The two pipes flow into a y-junction at the input to the 3 inch high flow convertor. the rest of the exhust system was the SLP catback with the two pipes exiting on the left side. The system drones like crazy around 2000 RPM. I tried replacing the orginal SLP muffler with a FlowMaster 50 series, but I got the same drone. I am tried of the loudness and am trying something different.

The Catco 4153 should be able to flow more then the single 3 inch cat. I have read reviews of Walker Quiet Flow 3 muffler and everyone says it is quiet and flows very well.

VincentZ28

iTrader: (2)

Your car had dual factory cats. Previous owner change them. They probably didn't want to buy two cats. People don't know this but dual cats cars doesn't make a deep loud drone sound like the single cat car.

ninetyone

iTrader: (2)

how much bigger was the SLP catback? You have to ask yourself if your stock exhaust has become a restriction yet. I would run the smallest pipe possible without it becoming a restriction or producing excess back pressure.Now a mandrel bent pipe should help smooth out flow though.

BruceEmbry

Please slow down, If you read my sigature, I'm the orginal owner of the 1982 Firebird that is listed. Brought it new in Jan 1982, Replace the engine in 1998 with 350 TunePort. Replace the orginal transmission with 4L60e in 2005. do a search on my name and you will find a bunch of stuff about my car.

The 82 bird came with the single Y-pipe, I upgraded the exhust system in 2000 with a full SLP system and single high-flow 3 inch convertor.

BruceEmbry

I do not have a stock exhust on the car. its a 3 inch SLP system with single high-flow 3 inch converter. I replaced the SLP mufflur over a year ago with a Flowmaster 50 series in a attempt to quiet down the car. The Flowmaster did not effect the loudness of the exhust system.

82 Firebirds did not offer an option with the dual convertor. A lot of parts are interchangable between the varous years of the Third Generation F-Bodys.

I will be receiving the Catco 4153 tomarrow. I received the Walker muffler and tail-pipes the other day. I going to assemble the whole exhust system on the ground this weekend. I am measuring everything and making sure it will all fit underneath the 82-Bird.

BruceEmbry

Hi All,
The OEM Spec system just went on the Bird.
The DRONE is gone!
Engine spins up faster now like it should.

After market exhust/Catback systems are not worth the money. All that you get is more noise, slower spin up of the engine, lost performance.

The original exhust system on my car with the LG4 used 2 1/4 inch pipe from the convertor back to the mufflur.

The new system has Dual Converter system with 2 1/2 inch pipe and Walker Quiet Flow 3 mufflur. The car now feels like it flying down the interstate, NO DRONE.
And the motor winds like crazy.