what is the size of the stock exhaust pipe [Archive] - GrandAmGT.com Forum

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timSSmokedGT1
01-31-2005, 12:51 PM
i am looking @ getting a borla exhaust system for my car but i wondered what inlet and outlet i would need ?

Kdawg207
01-31-2005, 12:54 PM
too small...lol

if you are getting a borla cat back...no worries....

you are just getting the muffler i would assume?

CoopGT
01-31-2005, 03:09 PM
If your getting the hole catback system don't worry it bolts right up.

Kdawg207
01-31-2005, 03:09 PM
lol...sorta what i already said no?

Ant
01-31-2005, 03:27 PM
2.25

mike2002
03-02-2005, 08:42 PM
2.25

im replacing the exhaust on a 2001 alero GLS, 3400. and the stock exhaust is 1 7/8"....i just looked at it 20 minutes ago while changing the oil

did gagt's get 2.25's, and ga se's / alero's get 1.875.

im getting pressure bent, custom, either 2.25 or 2.5

atc3434
03-03-2005, 11:43 AM
im replacing the exhaust on a 2001 alero GLS, 3400. and the stock exhaust is 1 7/8"....i just looked at it 20 minutes ago while changing the oil

did gagt's get 2.25's, and ga se's / alero's get 1.875.

im getting pressure bent, custom, either 2.25 or 2.5

1 & 7/8th's is the suck! I didn't know Aleros were so restricted. You're sure thats the size it is? Not doubting, as I've never looked under an Alero, but I would have figured it would be the same as the GA... GM doesn't usually cramp exhausts too bad.

mike2002
03-03-2005, 05:52 PM
100% sure it is. first i noticed it was so small, i can EASILY close my hand around it, i cant rap my hand around a 2 1/4" id pipe. so i measured the circumfrance and figured it all out to be 1.85 (1.875 is 1 7/8, my measurements where a little off)

so your saying yours was for sure 2.25 stock? im 99% sure the alero's and grandam use the exact same exhaust. i know the GT's different, maybe thats the confusion, GT's get 2.25, everyone else gets 1.875? i dont know, but a 2001 3400 alero has 1.875".

im having my exhaust put on tomorrow, most likely 2.25 pressure bent, ill see if they have 2.375" because that would fit around the muffler

i just think 2.5 is to big....ive got a pushrod v6 with 170hp, that will never see above 200 crank HP, intake, exhaust, dhp is all my car will ever see

2.5 is what they recommend for a near stock or very slightly modified GTP, and im 100hp short of a near stock GTP.

atc3434
03-03-2005, 06:11 PM
Well, I think 3" would be too big, but 2.5" isn't going to hurt the 3400, it's still small enough to develop good scavenging at lower rpms, and it will flow better on the topend than a smaller exhaust. And yea, I'm positive my stock exhaust was 2.25", I had done just a muffler for a while, it was 2.25 when I measured it. If guys have found gains w/ a better muffler and 2.5", I'd say thats the way to go. Mine ran better w/ the SLP.

mike2002
03-03-2005, 06:24 PM
that sucks that they did that to us alero owners...., because i see you have a SE, they have the same ratings as our alero's for power...oh well, ill just see bigger gains :D i think ill see if they can fit a 2.5" pressure bent pipe up there, when they were looking at it before, they said it would be tough...my muffler is a 2.25" ID, but i dont think it will be a bottle neck, its a strait through magnaflow. the biggest bottle necks would probalby be the bends, since a 2.5 probably gets to around 2.125 at the bends

could be a year thing too....99's did have some differences over the later years

MetaGTP1
03-03-2005, 10:04 PM
that sucks that they did that to us alero owners...., because i see you have a SE, they have the same ratings as our alero's for power...oh well, ill just see bigger gains :D i think ill see if they can fit a 2.5" pressure bent pipe up there, when they were looking at it before, they said it would be tough...my muffler is a 2.25" ID, but i dont think it will be a bottle neck, its a strait through magnaflow. the biggest bottle necks would probalby be the bends, since a 2.5 probably gets to around 2.125 at the bends

could be a year thing too....99's did have some differences over the later yearsWhy not mandrel-bent pipes? :)

mike2002
03-03-2005, 10:26 PM
i dont think a regular exhaust shop can do those... i was under the impression that its a very very expensive machine that most places dont have

ill see if they have 2 3/8" LOL, thats a good compermise!

AznGA
03-03-2005, 10:53 PM
Ya, SLP used to sell just the pipings (2.5" mandrel bent) but they do not sell those anymore. Local shops can charge you a lot for mandrel bent pipes.

GrahamKracka
03-03-2005, 11:10 PM
the gt stock exhaust is 2.25...and yes the borla would bolt right up

sprague67
03-04-2005, 12:28 AM
I also did not know that Alero's were that small, damn.