Twin 3 Inch Exhaust !? Anyone Done It?

[Joshbigt62r]

Would have to be 1k wouldn't it? I'm not really sure what mild steel prices are. Stainless would have to be what 1.2-1.4k for a decent cat back 4"? I really have no idea but just a estimate.

[jangles]

look up prices of off the shelf mufflers and resonators

[Joshbigt62r]

What brand? I tried searching and not a lot came up in 4" inlet.

[Deano 1]

$700-800.

Be nice do have a custom centre and rear muffler made that actually work, so we can run these big systems and not worrie as much about the cops.

My tomei system, flows awesome but it's stupid loud.

[Risking]

If I was to do a minimum of 5 systems using 4 inch mild steel with resonators and mufflers I could do them for $1200 each with flanges, bolts and gaskets.

4 inch mufflers and resonators aren't cheap

By comparison a 3.5in system doing 5 of them I'd say $880-990.

[Risking]

$1000 without the resonator.

[Shoota_77]

Does anyone have any actual knowledge of what effect (if any) it would have on an engine to have the cats staggered on a twin system? By that I mean having one cat slightly closer to the engine than on the other pipe to allow them to fit under the car better?

Like this picture (best photo I could find!)-

I tried Googling but couldn't really find any info.

[wedge_r34gtr]

Does anyone have any actual knowledge of what effect (if any) it would have on an engine to have the cats staggered on a twin system? By that I mean having one cat slightly closer to the engine than on the other pipe to allow them to fit under the car better?

Like this picture (best photo I could find!)-

I tried Googling but couldn't really find any info.

Any effect if any would probably be negligible.

It wouldn't hurt to stagger the cat’s so there equal distance from the turbo’s – that would ensure all things are indeed equal.

Edited February 27, 2013 by R31Nismoid

[R31Nismoid]

I can't remember what underside I saw, but there are some cars in the US doing it (modified). Can't see it as a problem as if you put them side by size "technically" they aren't event anyway given the front turbo is further away, and such setups work without issue. So you are effectively making it better.

Just ensure there is a cross over pipe somewhere if doing separate CATs/pipes.

[Shoota_77]

I can't remember what underside I saw, but there are some cars in the US doing it (modified). Can't see it as a problem as if you put them side by size "technically" they aren't event anyway given the front turbo is further away, and such setups work without issue. So you are effectively making it better.

Just ensure there is a cross over pipe somewhere if doing separate CATs/pipes.

Good point, I stupidly didn't think of that! In theory that makes it perfect! The offset would be nearly identical.

I remember when I was a tech at Holden when the whole crossover pipe thing came along. Late 90's early 00's from memory. If it only makes it a bit quieter then it's worth it.

[R31Nismoid]

Not so much the sound level, it's more the fact that going 3 cylinders per pipe, without a X-over, sounds really bad in a lot of cases.

Last car i heard like that didn't sound like a "RB" at all really. It was weird.

[gtr jet]

I always considered doing a separate pipe for each turbo thinking it would sound good but maybe I was wrong.

[NXTIME]

pretty sure there are some jap twin exhaust that don't have a crossover pipe....can't recall how good or bad they sounded though.

Edit: just checked a few u-toob vids and they sound like crap. I have always wanted a twin 3"...but I think a single 4" will do.

Dual 3" exhausts is the same as having a single 4¼" exhaust.

[Shoota_77]

pretty sure there are some jap twin exhaust that don't have a crossover pipe....can't recall how good or bad they sounded though.

Edit: just checked a few u-toob vids and they sound like crap. I have always wanted a twin 3"...but I think a single 4" will do.

Dual 3" exhausts is the same as having a single 4¼" exhaust.

Can you post some links Charlie? I must have shite searching skills as i couldn't find any!

[fatz]

i have a r33 gtr twin 3 inch system for sale if one of you f**kers want it

hks super dragger brand

[NXTIME]

Why are you selling it, Fatz? How loud?

[fatz]

its actually not that loud

just that it does not have any cats and i dont want to hack it up and put two in it

if your interested its still on the car and i can take you for a spin charlie

it has a mid muffler which quiets it down a bit

[fatz]

its probably worth a bit of coin as it hks

ma

make an offer

or trade me a 3.5 inch ti system

[Nee-san]

single exhaust single turbo always sounds best.

[cobrAA]

After reading this article http://www.modified.com/tech/modp-1102-exhaust-test-tech/

It seems like there could be a gain by going 3.5 inch. I already have the trust extension pipe which are 2x70mm. so to get perfect sizing, I should get myself a 4 inch cat-back to match the 2x70mm total exhaust diameter.

However, my setup is a RB26 with stroked 87mm piston and -5 with cams and all the supportive mods you could expect.. My cat-back is 3 inch right now. So, going 3.5 is quite easy, theres tons of aftermarket BUT theres very few 4 inch catback..

Whats your thought, anyone saw gain from 3.5 to 4 inch ? Should I really concentrate on having both the downpipe and catback ''flow-matched'' or simply stick in a 3.5 instead of my 3 inch and call it a day ?

P.S: I'm also keen about a 3.5 or 4 inch group buy in stainless steel!