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Question About Cat

WESTWD

By WESTWD,
in Engines & Forced Induction

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WESTWD Community Regular

WESTWD

Posted
Posted

Hey all,

firstly, i have done a search and could NOT find what i was after.

i got stock r34 exhaust system and am looking to upgrade to a catback and high flow cat.

i plan to go 2.5" but...

what size cat do i get?

2.25 (as stock system is 2.25) or 2.5??

thankyou

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(OO)SKYLINE(OO) Grand Master

(OO)SKYLINE(OO)

Posted
Posted

2.5" should do you just fine.

Cat, same size 2.5", high flow, the exhaust place will sort you out.

Some say you could go 3" but you would lose a bit of low down response, unless you tune your car.

You planning on getting a canon or an oval shape muffler?

(OO)SKYLINE(OO) Grand Master

(OO)SKYLINE(OO)

Posted
Posted

Depending on how loud the Canon muffler is...

All the Canon mufflers I have owned are loud, but they all had 4.5" out pipes LOL!

In most cases you probably will to dull the noise / drone down a bit, but I think a resonator will effect the exhaust flow.

Or you can go for a Canon but with a silencer bolted into it.

If you get a Oval shape, you won't need a resonator, as Oval shape ones are mostly fairly quiet.

Juliet (llama au) has a Fujitsubo turbo back exhaust and you can hardly hear it.

Fujitsubo seem to do a great job.

(OO)SKYLINE(OO) Grand Master

(OO)SKYLINE(OO)

Posted
Posted

Yeah they still are high flow.

I think it is how the muffler is made / fabricated, the metal on the inside of the Oval shape muffler dulls out the noise better then the Canon mufflers, but can still retain a good flow.

If anyone on SAU can explain how this is done the post a way... :(

AYW550 Collaborator

AYW550

Posted
Posted
ok, cheers,

are oval tips high flow though?

i put an oval stainless dual tip power pro muffler on mine and its very high flow (you can see straight thru it via two, 2.5 tubes inside the muffler)

but it was just as loud as any cannon even with a resonator and i later had to put a muffler+resonator 2in1 muffler in the system right after my extractors and before the other resonator!

AYW550 Collaborator

AYW550

Posted
Posted
Yeah they still are high flow.

I think it is how the muffler is made / fabricated, the metal on the inside of the Oval shape muffler dulls out the noise better then the Canon mufflers, but can still retain a good flow.

If anyone on SAU can explain how this is done the post a way... :(

i think its a combination of a few factors,...the type of metals used, the type of sound deadening material used to pack the muffler and the fact that inside a high flow oval muffler there is simply more surface area to obsorbe the sound waves

(OO)SKYLINE(OO) Grand Master

(OO)SKYLINE(OO)

Posted
Posted
i think its a combination of a few factors,...the type of metals used, the type of sound deadening material used to pack the muffler and the fact that inside a high flow oval muffler there is simply more surface area to obsorbe the sound waves

Thanks for that! :(

Where as a Canon muffler has less surface area to obsorbe the soundwaves... Hence it being louder...

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