2.5" Or 3"?

[senilykSkylines]

Hey guys,

I have got a boost T ready to hook up but I want to get an exhaust done first. I have been recommended by others to get a 3" turbo back exhaust so I booked in my car for a quote. The exhaust guy said that 3" is too big and will be too loud (I don't want it loud. just performance) and suggested that all I would need is to take out the cat converter and run a straight 2.5" pipe through from where the cat was. The rest of the stock pipe is 2.5" but it changes to a 2" half way down which he recons is all I need to take out in order to get some good performance.

Getting told millions of different things. It is cheaper to do the 2.5" obvously, but is it worth it?

Some help and/or experience of different exhausts would be great thanks!

[R31Nismoid]

3" or bust!

A proper 3", with two decent mufflers, will not be loud at all.

Under 90dB which is very quiet.

[N1GTR]

Bigger the better.

[StealthX]

Go 3", add in an extra resonator and you'll be fine. Best of both worlds.

BTW, did a professional exhaust fabricator advise you to take out the cat on a street car?

I'd be heading to a different exhaust shop if I was you...

[defari]

i got 3inch straight through, its f**ken loud.

[The Dan]

Sounds like the guy you are talking to is a tool. Depending on where you are, there are massive fines for running no catalytic converter.

3" all the way but spend some decent money on a good quality rear muffler. You could run 5 inch all the way, it's the rear muffler that will determine 85-90% of the sound that comes out of it

[Harey]

Sounds like the guy you are talking to is a tool. Depending on where you are, there are massive fines for running no catalytic converter.

3" all the way but spend some decent money on a good quality rear muffler. You could run 5 inch all the way, it's the rear muffler that will determine 85-90% of the sound that comes out of it

His location says NZ so I am pretty sure they are not required by law to run a catalytic converter.

As everyone has said, bigger the better, the type of muffler will determine most of the sound. 3" minimum.

But yeah guy is still a tool, my 3" exhaust is super quiet. Depends on the mufflers

Edited August 25, 2010 by Harey

[N1GTR]

If you don't have to have a cat, if that is correct, do you have to have mufflers?

If not, does the exhaust have to exit past the diff?

If not, I would honestly have a side pipe exiting just after the trailing edge of the passenger door

[KiwiRS4T]

Cat is not currently required in NZ. There is a noise limit.

To OP: get the three inch now or you will be doing it again later. Also find another exhaust shop. With the right muffler at the end you will not be too loud or if you want you can stick in a resonator in the middle.

[senilykSkylines]

3" or bust!

A proper 3", with two decent mufflers, will not be loud at all.

Under 90dB which is very quiet.

Many thanks guys,

Depends what you mean by "quiet"

I got a 3-4 inch tip on the back at the moment and it rumbles. It only gets my ears going slowly up a hill. 90dB unless I am mistaken is rather loud. I've got a little bubby expected early next year so I want it to be soft on his/her ears... but I want performance as well

cheers

[R31Nismoid]

It'll be less than 90dB, Jap 2x muffler setups can be 86dB quite easily and that honestly is super quiet.

You cannot have performance & total silence mate, just how it is.

[MrR33666]

dude if your gonna be drivin a baby around in it dont bother. 3" from the turbz back is the way to go but thats gonna be too loud for a baby. back preasure and turbos dont mix so the 2.5" is a no go.

[The Dan]

From what I hear, babies sleep through pretty much anything so just go 4inch straight and forget about it

[N1GTR]

A mate has a very young child, and shes often in his gtr. As soon as ge goes around the block he says she's asleep. Stockish GTR with a kakimoto exhaust.

He's been doing this for ages, I think his girl is about to turn 2yo

[senilykSkylines]

I'm not expecting it to be quiet. I want a rumble... but I just don't want it loud enough to get my ears...or the little one's.

[TUF250]

i got a 3inch turbo back on mine, it is barely louder than stock (two proper mufflers), just a bit deeper. What I did notice was a big bump up in performance. definately worth it!!

[R31Nismoid]

I'm not expecting it to be quiet. I want a rumble... but I just don't want it loud enough to get my ears...or the little one's.

What ive reccomended above mate, trust me, will not be loud/drone or annoying.

Anyone of the Vic guys thats seen my car will tell you that you don't even notice it.

@ 2000rpm, no stereo and tiny bit of throttle, i can't even hear it and my car has all the sound deadening removed.

[89CAL]

get something like a varex (from x-force) if you want the best of both worlds. Performance when you want, quiet when you want

[GT-T 1998]

ive got a r34 GTT i was wondering if anyone knows if you can get extractors with a 3inch outlet .. ive got from the catback back 3inches but turbo to catback is just stock. i want to hole thing 3inch.

[KiwiRS4T]

ive got a r34 GTT i was wondering if anyone knows if you can get extractors with a 3inch outlet .. ive got from the catback back 3inches but turbo to catback is just stock. i want to hole thing 3inch.

You can get up to 5in if you want!