Exhaust changes to the 3.0R/B... worthwhile?

[SegR]

Is trying to open up the exhaust on a 3.0R likely to make any appreciable gain to performance? (with a tune to follow)

Or is it going to achieve little other than more freedom for the H6 to talk a little louder?

Looking at anything from outer muffler replacement (quads) to changes to the stock pipes, cats and any other mufflers remaining in the system.

Obviously there's plenty to be gained for a turbo... but less information seems to be available for N/A vehicles and although a few people seem to have done 3.0R[B] mods in this area, nobody talks very much about performance gains.

[Robbks]

from speaking with a number of very experienced guys with respect to Subies, tuning, rallying, conversions, etc
the overwhelming advice i got from them regards to exhausts was the following.

with regards to the headers/ front section of the exhaust
This is where any gains will be made

-remove the 3 cat converters in the headers (one on each seperate bank and the 2-1 pipe which is a third cat)
-replace with one high flow (200cell or 100cell) cat on each bank
-re-install factory o2 sensors in their stock locations
-keep the 2-1 collector in the stock location
-keep the pipe diameter the same as stock

this is exactly what i'm doing
i have currently only done the 2-1 (rearmost cat converter) as seen below


but next is to remove the front two and have it tuned.

The advice given to me fopr the rest of the exhaust is, keep the centre section the same diameter as it is, removing the resonator will simply change the note, no performance difference
and changing the rear mufflers do basically nothing as far as power goes. it's all about sound

I'm not expecting much gain at all, just a little more smoothness and economy
but even with just that one cat removed, i have noticed the low-down flatspot (1500-200rpm) i had has disappeared and the car is much easier and smoother to creep around in that rev range in traffic, it was always very jerky, but is now much nicer

[swingn]

Biggest gain is going to come from the tune itself.

If you're planning on doing a full exhaust & maybe even headers, then of course you are going to get a bigger power gain etc etc etc... If you're talking about just doing a catback, the gains are damn near negligible... But the sound will make you feel like your going faster

[SegR]

Thanks Rob. Good info. With those cat changes would the system be likely to meet emissions standards and would it cause the ECU to freak out until a tune is done?

but even with just that one cat removed, i have noticed the low-down flatspot (1500-200rpm) i had has disappeared and the car is much easier and smoother to creep around in that rev range in traffic, it was always very jerky, but is now much nicer

Really - that's surprising - I wouldn't expect it to have made that much difference. It's the low-end sluggishness that shits me at the moment really. Can't complain about performance from 3000rpm+ (the car seems to just wake up at about the 3000rpm mark).

Biggest gain is going to come from the tune itself.

If you're planning on doing a full exhaust & maybe even headers, then of course you are going to get a bigger power gain etc etc etc... If you're talking about just doing a catback, the gains are damn near negligible... But the sound will make you feel like your going faster

I expect the sound also results in an increase in mass of the driver's right foot, assisting the speed increase further.

Headers... couldn't be bothered and probably beyond what I'd want to spend anyway. I'm trying to work out the balance between price and benefit (sound, appearance, performance, boner inducement) - this will of course be different for everyone.

[Robbks]

the standard car will probably not meet emissions now it's a few years old anyway.
basically as long as you can show you have cats and they're working you should be fine.
butthe ECU tune will throw it off anyway.

i'm not expecting any CEL issues given I'm putting cats back in teh same spots in relation to the o2 sensors. if there's problems, my tuner will just turn them off

[SegR]

-remove the 3 cat converters in the headers (one on each seperate bank and the 2-1 pipe which is a third cat)
-replace with one high flow (200cell or 100cell) cat on each bank
-re-install factory o2 sensors in their stock locations
-keep the 2-1 collector in the stock location
-keep the pipe diameter the same as stock

this is exactly what i'm doing

Did you end up finishing these mods, Rob or is this still a work in progress?

Without a dyno run before the mods, after the mods, then again with a tune, I guess it's hard to quantify the real benefit - but in your opinion, is the above work worth the time, effort and money?

I'm planning how far I should delve into my bank account before getting the tune done!

[Robbks]

still in progress.
a few setback with other minor things needing attention (aircon re-gas, CV boots, etc)
but with the small gains noticed from the removal of the rear cat, and the restrictions that are still to be eliminated, i think they will be worthwhile

on just about any car a full exhaust re-vamp will set you back in the vicinity of $1000 when you're replacing cats aswell so i don't think it's an outrageous expense

[B8ZE]

from speaking with a number of very experienced guys with respect to Subies, tuning, rallying, conversions, etc
the overwhelming advice i got from them regards to exhausts was the following.

with regards to the headers/ front section of the exhaust
This is where any gains will be made

-remove the 3 cat converters in the headers (one on each seperate bank and the 2-1 pipe which is a third cat)
-replace with one high flow (200cell or 100cell) cat on each bank
-re-install factory o2 sensors in their stock locations
-keep the 2-1 collector in the stock location
-keep the pipe diameter the same as stock

The advice given to me fopr the rest of the exhaust is, keep the centre section the same diameter as it is, removing the resonator will simply change the note, no performance difference
and changing the rear mufflers do basically nothing as far as power goes. it's all about sound

I'm not expecting much gain at all, just a little more smoothness and economy
but even with just that one cat removed, i have noticed the low-down flatspot (1500-200rpm) i had has disappeared and the car is much easier and smoother to creep around in that rev range in traffic, it was always very jerky, but is now much nicer

I got quoted roughly around $1200 to have this done including new mufflers & piping from the mufflers back whilst keeping the standard tips. Does it seem like a fair price?

[Robbks]

I got quoted roughly around $1200 to have this done including new mufflers & piping from the mufflers back whilst keeping the standard tips. Does it seem like a fair price?

Sounds about right for what i costed out
$250 per cat and $250 per muffler + pipe, flanges, etc

[Blitzen06Wgn]

I recently fitted a tow bar to my 3.0R wagon. Being a bit of a bogan from way back, while I had the mufflers off I thought I'd see what it sounded like.

I was surprised at how quiet the exhaust was with no rear mufflers. I would say definitely street legal and a nice note too.

Had me thinking that you could save money by just having straight pipes at the rear instead of mufflers. I'm not sure how that would affect the power dynamics, economy etc.

Interesting though!

[SegR]

Ha interesting. Can't say I've tried running with no muffs.

Has anyone here run a 3.0R (auto or manual, preferably auto) with STI quads and can you comment on their sound? The Phat quads sound awesome on GTs and spec B's but on the auto N/A, drone at ~2700RPM and it bugs the hell out of me.

[Finky]

I'm just running strait pipe and I think it sounds unreal.. But the drone is pretty annoying on the freeway but just cruze at about 120km and it goes silent haha

[SegR]

You're nuts :-p

The quads I have only drone in a band of about 300RPM and are completely fine outside of that. I'm just picky.

[Blitzen06Wgn]

Nice wheels you have Finky. The white looks really good against the red Blitzen. I'm not sure I like the Blitzen wheels any more - they look a bit like BMW X5 or Ford XR5. A pity the 12 spoke STI wheels are so expensive as they look awesome.

[bates91]

Nice wheels you have Finky. The white looks really good against the red Blitzen. I'm not sure I like the Blitzen wheels any more - they look a bit like BMW X5 or Ford XR5. A pity the 12 spoke STI wheels are so expensive as they look awesome.

sell your blitzens then...
theyre rare enough that i think theyd go for a pretty good price