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

 

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?

 

Most aftermarket y-pipes are 3".

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

 

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

 

3 inch into the Flowmaster merge.

 

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

 

stainless works makes a 2.5". I have it with cats and put down numbers in sig.

 

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.

 

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.

 

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.

 

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.

 

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.

 

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!

 

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...

 

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.

 

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.

 

Ok so how does this look for the y pipe build? Should have everything here besides the mandrel bends, and the clamps. Let me know if I am going 100% in the right direction

Flowmaster Y collector 3 x 4 x17.5

Flowmaster 3 inch to 3 inch ball flange kit (2 pairs)

Flowmaster reducer (Wrong size though) 3 inch to 4 inch

Magnaflow universal 59959 3 inch center spun mettalic cat

 

I got my 4" x 3" reducers from Summit, they were only sold in pairs.

http://store.summitracing.com/partde...5&autoview=sku