Y pipe build size

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Feb 26, 2007 | 08:41 PM

CAMJAG

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From: CT

Y pipe build size

Putting on a set of QTPs and gona hve my y pipe cutom built with high flow cats and flowmaster y collector. Should I have my y pipe built 2.5 inch or 3 inch

Feb 26, 2007 | 08:43 PM

NHRAMAN

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From: Vancouver,[KITSILANO].B.C. Canada *WestCoast*

Go 2.5..it is all u need + if u lower your car you will be happy you did...

Feb 26, 2007 | 09:05 PM

CAMJAG

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Quote:

Originally Posted by NHRAMAN

Go 2.5..it is all u need + if u lower your car you will be happy you did...

My car will not be lowered. Are most of the aftermarket y pipes 2.5 inch?

Feb 27, 2007 | 12:04 AM

TheBlurLS1

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Most aftermarket y-pipes are 3".

I'd do 3" from the headers, into a Flowmaster merge.

Feb 27, 2007 | 12:11 PM

Ragtop 99

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I'd do 3" no question when running cats.

Feb 27, 2007 | 05:12 PM

Fratsit

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3 inch into the Flowmaster merge.

Feb 27, 2007 | 06:08 PM

NHRAMAN

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NO LOWERING.....I agree then..... go 3" .mines 3" and speedbumps are troublesome to say the least.

Last edited by NHRAMAN; Feb 28, 2007 at 03:47 PM.

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Feb 27, 2007 | 10:01 PM

ls2 bait

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mine car is lowered almost 2 inches and i have a 3" y with flowmaster merge-as long as u dont drive like the duke brothers u will be just fine.

Feb 28, 2007 | 09:14 AM

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lsx24

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2.5" inch collector is what will hold back the flow. With the Long Tubes you would be better off with a 3" or even a 3" x 3" ---> 3.5" collector. That would be best. Then 3.5" back to your catback. If going custom, they should be able to tuck it up there nicely, such that it won't hang low. With a ypipe your collector will be the biggest limiting factor in flow.

Feb 28, 2007 | 09:38 AM

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gnomee

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The one my exhaust guy made me earlier this month was 3" into the flow master merg collector. No numbers, but It fits just fine.

Feb 28, 2007 | 11:44 AM

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camaroguy26

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is the MAC ORY 3" or 2.5"? I'm trying to get some cats for it but won't see the car for 3 more months and trying to get my cats before I do get home.

Feb 28, 2007 | 11:54 AM

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Ping King

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just remember a flowmaster merge with 3 inch primaries only comes out in 3.5 or 4 inch.

Ive built several 3" y pipes that tucked up perfect.

Feb 28, 2007 | 12:33 PM

#14

CAMJAG

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Thanks for all the info... I will be building it with those magna flow spun cats, (still trying to figure out which style) fowmaster collecters, and flowmaster merge. 3 inch it is!

Feb 28, 2007 | 01:37 PM

#15

chrs1313

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Mine is a custom 3in y with my qtps and it fits really nice...also might wanna get 3in too if you are not getting madrel bends...

Feb 28, 2007 | 03:02 PM

#16

CAMJAG

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Quote:

Originally Posted by lsx24

On Flowmaster's web site they have the Y collector in 3 X 3.5 X 17.5 AND 3 X 3.5 X 18.5

Get the longer one or the shorter one?

Feb 28, 2007 | 03:32 PM

#17

lsx24

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Quote:

Originally Posted by CAMJAG

On Flowmaster's web site they have the Y collector in 3 X 3.5 X 17.5 AND 3 X 3.5 X 18.5

Get the longer one or the shorter one?

With only an inch difference, it's not going to matter. But double check, there may be something else different between those two other than length...sometimes the collector size is different for different applications.

Feb 28, 2007 | 03:38 PM

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TheBlurLS1

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I think you should do a 3" x 4" Flowmaster merge with a 4" x 3" reducer, since you'll have to have one anyway. This is what QTP uses on their stuff, and works great for power. It also lets you hack the reducer one day and have a 4" system like mine.