Exhuast question [Archive] - GrandAmGT.com Forum


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05-30-2013, 08:55 PM
If I plan on upgrading to a new exhaust in the future like a borla what catalytic coverter is recommened for a GA... Oviously when getting a new exhaust a new cat is good to replace, what kin and where can I get it.

05-30-2013, 11:50 PM
there's threads all over the place about cats. Honestly if yours still has the factory cat I'd keep it till it fails. a new OEM one is close to 800 dollars. Non-OEM cats and highflow cats are 50/50 sometimes you won't get an SES, but sometimes you will. I replaced mine a few years ago, and have had a couple codes for cat deficiency. But since the summer months hit, I haven't had a problem.

05-31-2013, 12:40 AM
Milzy makes a custom downpipe which has the option of a high flow magnaflow cat or no cat at all.


05-31-2013, 03:48 AM
Okay, what are your plans for the car first of all? You planning to do lots to the engine? Ported heads, ported intake manifolds, cam, headers, etc.

If not and I see in your info you're from Connecticut, you probably have a yearly emissions test to worry about. Is the catalytic converter original on the car? Is it clogged? Have an SES light on because of it? Replace it with an OEM type, if you don't then there's a good chance it'll fail prematurely and/or throw an SES light after awhile.

Now, for an exhaust setup if you don't plan on doing anymore to the engine other than a CAI:

>stay with the 2.25" pipe size
>replace the factory resonator with a high flow resonator or glasspack
>Flowmaster 80 muffler
>use exhaust tips of your choice

I used that setup, lasted me over four years before the Flowmaster rotted away from it's hangers and a few welds.

05-31-2013, 09:14 AM
get a milzy downpipe with hi flow cat and a PCM tune so the hi flow cat will not throw a code which it will and you will get ur GAs full potential with a tune. I love my tune now i just gotta grab that down pipe

LINK DOWNPIPE (http://www.milzymotorsports.com/mms-stainless-downpipe-for-99-05-grand-am-n-body/)

LINK PCM TUNE (http://www.milzymotorsports.com/mms-3400-powertrain-control-module-pcm/)

I have a pacesetter cat back with 2.5" pipping and i had it ceramic coated. It sounds great after it broke in and i have 20% better throttle responds and torque. A basic PCM tune will make ur shifting more peppy with a few other benefits.

I dont like Borla because its the stock size piping and its $800+ plus its mostly quite and doesn't have a gargle or growl which i happen to like.

05-31-2013, 10:19 AM
For the final time god dammit, the Borla from pfyc is $750ish shipped. NOT $800+ lol You get what you paid for, a quality exhaust that will last you the lifetime of your car but also has a nice rumble to make your car stand out more but also not too loud to attract a flock of cops. Not to mention compared to the stock pressure bends the Borla mandrel bends create better flow. I couldn't believe the bends that I was looking at when I took the stock pipe out that goes over the rear axle.

And you're definitely wrong on the fact that it is "quiet" and has no "growl/gargle" to it lol. It is by no means loud but it also by no means is quiet.

Also its nice to replace the cat but its not necessary unless yours in clogged, mine was clear as day looking at it. Milzy makes a downpipe with a magnaflow high flow cat.