2 1/2" mufflers on stock 2 1/4" pipes?

91LX2Bfast · 10-27-2001, 02:46 PM

Hey, haven't had to ask a question for a while untill now.
I have been reading that alot of people have 2 1/2" mufflers welded onto their stock pipes. How does this work? Is the outside diameter of the 2 1/4" pipe close enough to the 2 1/2" ID of the muffler? Or do they use a reducer? Just wondering because my brother is about to purchase some mufflers for his 99GT.
I just put 2 1/4" in Flows on my stang because thats all that I thought would fit. As always, any help is appreciated.

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1997 Thunderbird 4.6L: Dynomax cat-back, MN-12 perf. offroad downtubes and Y-pipe w/ Magnaflow resonator, 80mm MAF with cone filter, B&M trans cooler, Inject-Tech chip, MAC U/D pulleys, KVR front brake upgrade. 15.2 @ 91 before exhaust & pulleys. Not bad for a 3800lb auto 4.6L

No Longer own: 91 LX 5.0L 5 spd

Mercury · 10-27-2001, 03:32 PM

They use a reducer.

Have 2 1/2 inch 40 series flows on my 2000 GT.

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64 1/2 "D" code Red Mustang Coupe. 289, C4, Mallory duel point. Ported & Polished 65 heads shaved .01 with 351 valves, 11:1 comp, 1.7:1 rockers, blue wolverine lumpy cam, modified 4100 Hipo 4 barrel. GT Apperance pkg. And to many others to list

2000 Perf Red Mustang GT. 5spd. BBK Underdrive pulleys, Flotech off-road H pipe. Hurst T-Handle, 40 series Flowmasters, Steeda Tri-Ax. Ordered 4:10's.

64 1/2 red 6cyl coupe. Future resto.

ny mustang gt · 10-27-2001, 05:51 PM

anything to help me here to im in the same perdicament exhaust searching is exhausting ha ha. looking into a bassani for my o1 gt automatic

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2001 4.6 gt automatic bone stock for now

DOMIN8R97 · 11-01-2001, 02:26 PM

Are you guys sure the stock exhaust is 2 1\4??? I was always told that the stock exhaust was 2 1\2 in. I know the tails on the '99-up GT's get wider at the tails but I think the rest of the exhaust is 2 1/2" but I might be wrong.

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Red '97 Mustang GT
Auto
Bone Stock!
(Except for silencer)

96GTfanatic · 11-01-2001, 11:48 PM

for 96 and im sure the same for 01, exhaust was 2 1/2. i know this because i purchased 2 1/2 inch exhaust, matched it up to the old stock one, and it was exact same size.

91LX2Bfast · 11-02-2001, 12:52 PM

No, the stock is 2 1/4". Almost all aftermarket uses bigger 2 1/2" pipe, which will bolt up to the stock stuff fine. I believe the newer Cobra's have 2.5", and aftermarket catbacks are 3" for them, but the GT's have 2 1/4" stock w/ 3" tips.

10-27-2001, 02:46 PM	#1
91LX2Bfast Registered Member Join Date: Dec 1999 Location: Warrington, PA Posts: 694	2 1/2" mufflers on stock 2 1/4" pipes? Hey, haven't had to ask a question for a while untill now. I have been reading that alot of people have 2 1/2" mufflers welded onto their stock pipes. How does this work? Is the outside diameter of the 2 1/4" pipe close enough to the 2 1/2" ID of the muffler? Or do they use a reducer? Just wondering because my brother is about to purchase some mufflers for his 99GT. I just put 2 1/4" in Flows on my stang because thats all that I thought would fit. As always, any help is appreciated. ------------------ 1997 Thunderbird 4.6L: Dynomax cat-back, MN-12 perf. offroad downtubes and Y-pipe w/ Magnaflow resonator, 80mm MAF with cone filter, B&M trans cooler, Inject-Tech chip, MAC U/D pulleys, KVR front brake upgrade. 15.2 @ 91 before exhaust & pulleys. Not bad for a 3800lb auto 4.6L No Longer own: 91 LX 5.0L 5 spd

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10-27-2001, 03:32 PM	#2
Mercury The Redneck James Bond Join Date: Sep 2000 Location: Fayetteville NC Posts: 1,707	They use a reducer. Have 2 1/2 inch 40 series flows on my 2000 GT. ------------------ 64 1/2 "D" code Red Mustang Coupe. 289, C4, Mallory duel point. Ported & Polished 65 heads shaved .01 with 351 valves, 11:1 comp, 1.7:1 rockers, blue wolverine lumpy cam, modified 4100 Hipo 4 barrel. GT Apperance pkg. And to many others to list 2000 Perf Red Mustang GT. 5spd. BBK Underdrive pulleys, Flotech off-road H pipe. Hurst T-Handle, 40 series Flowmasters, Steeda Tri-Ax. Ordered 4:10's. 64 1/2 red 6cyl coupe. Future resto.

10-27-2001, 05:51 PM	#3
ny mustang gt Registered Member Join Date: Sep 2001 Location: wappingers falls ny usa Posts: 7	anything to help me here to im in the same perdicament exhaust searching is exhausting ha ha. looking into a bassani for my o1 gt automatic ------------------ 2001 4.6 gt automatic bone stock for now

11-01-2001, 02:26 PM	#4
DOMIN8R97 Registered Member Join Date: Aug 2001 Location: Arlington Heights, Illinois Posts: 29	Are you guys sure the stock exhaust is 2 1\4??? I was always told that the stock exhaust was 2 1\2 in. I know the tails on the '99-up GT's get wider at the tails but I think the rest of the exhaust is 2 1/2" but I might be wrong. ------------------ Red '97 Mustang GT Auto Bone Stock! (Except for silencer)

11-01-2001, 11:48 PM	#5
96GTfanatic Registered Member Join Date: Jul 2001 Location: Philadelphia Posts: 93	for 96 and im sure the same for 01, exhaust was 2 1/2. i know this because i purchased 2 1/2 inch exhaust, matched it up to the old stock one, and it was exact same size.

11-02-2001, 12:52 PM	#6
91LX2Bfast Registered Member Join Date: Dec 1999 Location: Warrington, PA Posts: 694	No, the stock is 2 1/4". Almost all aftermarket uses bigger 2 1/2" pipe, which will bolt up to the stock stuff fine. I believe the newer Cobra's have 2.5", and aftermarket catbacks are 3" for them, but the GT's have 2 1/4" stock w/ 3" tips.