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Discussion Starter #1
now that i purchased the "second gen" mazzuri headers which is 2.5", ive been thnking about replacing the 2-1 part of the y-pipe with a 3".

i've discussed with Daniel (maker of mazzuri headers) and he said it can be done, but my question is, besides the sound of the 3" being louder than the 2.5", are there any other differences? there has to be some kind of performance differences, even its just a little. has anyone actually owned both 2.5" and 3" y-pipes? and if going 3", is it going to sound nasty?

p.s.
im shooting for the dual exhaust setup, which is just 2.5" or 3" splitting into two and end with a oval exhaust (which reduces the loudness compare to round canister exhaust)
 

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now that i purchased the "second gen" mazzuri headers which is 2.5", ive been thnking about replacing the 2-1 part of the y-pipe with a 3".

i've discussed with Daniel (maker of mazzuri headers) and he said it can be done, but my question is, besides the sound of the 3" being louder than the 2.5", are there any other differences? there has to be some kind of performance differences, even its just a little. has anyone actually owned both 2.5" and 3" y-pipes? and if going 3", is it going to sound nasty?

p.s.
im shooting for the dual exhaust setup, which is just 2.5" or 3" splitting into two and end with a oval exhaust (which reduces the loudness compare to round canister exhaust)

2.5" exhaust can hold a lot of HP, more than a N/A IS could give out, so a 3" won't really do anything for power, but I have it and it sounds deep.
 

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Ive Herd Its Not Good To Put In A 3" Unless You Have A Turbo Or Supercharged Because You Are Going To Loose Alot Of Torque.. Thats Why When I Get My Headers And Y Pipe Ima Have To Go Back Down To A 2.5" But Ima C How My Car Reacts First To The 3"
 

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Ive Herd Its Not Good To Put In A 3" Unless You Have A Turbo Or Supercharged Because You Are Going To Loose Alot Of Torque.. Thats Why When I Get My Headers And Y Pipe Ima Have To Go Back Down To A 2.5" But Ima C How My Car Reacts First To The 3"
Why do you capitalize every word?
 

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Ive Herd Its Not Good To Put In A 3" Unless You Have A Turbo Or Supercharged Because You Are Going To Loose Alot Of Torque.. Thats Why When I Get My Headers And Y Pipe Ima Have To Go Back Down To A 2.5" But Ima C How My Car Reacts First To The 3"
You heard wrong. Check my old dyno, my car made more wtq at 2,000 RPM than when it was stock at it's peak.
 

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If I could do mine again I would go with the 2.5, Dont get me wrong the SRS power gains were great but it was way to loud. I brought mine to a muffler shop to redo the axle and fix the height issue.
 

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now that i purchased the "second gen" mazzuri headers which is 2.5", ive been thnking about replacing the 2-1 part of the y-pipe with a 3".

i've discussed with Daniel (maker of mazzuri headers) and he said it can be done, but my question is, besides the sound of the 3" being louder than the 2.5", are there any other differences? there has to be some kind of performance differences, even its just a little. has anyone actually owned both 2.5" and 3" y-pipes? and if going 3", is it going to sound nasty?

p.s.
im shooting for the dual exhaust setup, which is just 2.5" or 3" splitting into two and end with a oval exhaust (which reduces the loudness compare to round canister exhaust)

Rather than going 2 into 1 and then back into 2 with a 3 inch "1", why not run the two 2.5" pipes all the way to the back? I've thought about doing this myself . . . getting rid of the y-pipe all together and just running 2 2.5" pipes from the header all the way to the back of the car. The problem (for me) is that there are literally no shops around me that can do custom mandrel bends but there definitely seems to be enough room under the car to run 2 pipes next to each other all the way back.
 

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Discussion Starter #10
Rather than going 2 into 1 and then back into 2 with a 3 inch "1", why not run the two 2.5" pipes all the way to the back? I've thought about doing this myself . . . getting rid of the y-pipe all together and just running 2 2.5" pipes from the header all the way to the back of the car. The problem (for me) is that there are literally no shops around me that can do custom mandrel bends but there definitely seems to be enough room under the car to run 2 pipes next to each other all the way back.
i think someone has done that, and im not quite feeling the sound quality
YouTube - IS300 Dual Exhaust WOT
 

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i think someone has done that, and im not quite feeling the sound quality
YouTube - IS300 Dual Exhaust WOT
Ahhh no. ;) That person did an . . . 'interesting' thing to make their dual exhaust. Back just before the rear muffler ection they created what looks almost like a T joint in the 2.5" pipe and ran the second exhaust pipe under the trunk (or near it) at a 90 degree angle over to the other side of the car . . . it was certainly one way to go dual . . . not what I would have done - but whatever floats your boat. :)

The person who did this posted pictures in this forum somewhere if you want to search for it . . . I looked at them months ago and all I remember thinking is that there is no way both mufflers have an equal volume of exhaust gas going to them because of the funky / wierd "T" shaped hookup they did to tap the exhaust for the second muffler.
 
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