WREXY

I must admit that from John's knowledge, his mature writing style, plus being a doc, I too thought he'd be at least over 35. When I saw the young lad before I picked him up from the airport last year, I freaked out. I thought that John may have sent someone else in his place to map my car. Turned out the young lad was indeed John.

Good luck to you my friend.

Cheers,

George.

[Edited by WREXY - 11/1/2003 12:34:39 AM]

john banks

A little surprised at this - there was only 7 WHP difference between a really noisy Blitz Nur Spec backbox on the same bit of road, on the same day, with Delta Dash Road Dyno. Torque drop was smaller and mostly due to running 1 PSI less because of the change in backbox.

We wanted to compare what is about the loudest backbox we've come across against an STi 5/6 backbox which is basically like the twin pea shooter the car comes with as standard but with a different tip.

Spec of the car:
MY00 UK turbo
TD05 at 20 PSI dropping to 17 PSI at the top
Gruppe S headers
FMIC
PE T75 3" > 2.5" flange
Magnex 2.5" resonated centre section

Power was 272 WHP with the Blitz and 265 WHP with the STi backbox. Up until 3800 RPM there was no difference at all, with a small difference in the midrange thought to be due to the slightly lower boost reached with the STi exhaust.

The difference in noise was incredible, with the STi backbox making it a really pleasant quiet car (tyre roar and wind noise was louder than the exhaust, induction noise was at least as loud as the exhaust), I'm not sure if you had earmuffs on if you could tell the 2.6% difference in power?

I am tempted to get a quiet backbox for daily use based on this.

Anyone else getting a headache and thought that the gain was rather more than this or am I just getting too near to 30 and find a loud Subaru rather embarrassing these days?
Cue.. sport bonnet, quiet exhaust?

[Edited by john banks - 10/30/2003 7:32:13 PM]

ustolemyname??stevieturbo

iTrader: (1)

And what was it like for power with the Magnex backbox??

I dont see too many reasons why a car cant be effectivley silenced without too much restriction. They dont all need to be as loud as the Blitz, even if they may sound faster to some.

john banks

He's not got the Magnex on it yet, will try a 6x4 next, and try to do before/after on the same day, as climatic conditions may well easily have more effect than the exhaust change.

9 BHP is not to be sniffed at of course, but I'm not sure the noise is worth it for me.

dowser

When running just under 300 hp, I perceived a large difference between STi5 backbox and Magnex (not only due to boost drop)....it's the only reason I run the Magnex (quiet is subjective, CH is very conservative ). I never road-dyno'ed it, maybe I should...OE STi item is still hanging in my garage. I don't agree it flows same as OE pea-shooter though, it's quite a lot louder.

Could it be a faulty Blitz?

Richard

john banks

Can't see what can be faulty with the Blitz it is just a pipe it is not bashed or anything, and with a light shone down it is straight through. It wasn't leaking, and it sounded great when you are pushing it and the car is rapid. It sounds a lot slower with it off, but the figures tell another story.

Maybe the STi backbox is different, sure a few people on here said they thought it was the same as the pea shooter. I've always thought the back box made the most difference to noise whereas the downpipe decatting seems to make the most difference to power.

The backbox choice makes the difference between being able to drive for hours without fatigue or for 20 mins at a time.

SlowBoy

iTrader: (1)

I'm surprised it made that much difference.

I also thought BBs were more cosmetic (noise and looks) than performance orientated, compared to any other part of the exhaust. Always assumed you'd be looking at 5-7bhp increase, up to 10 for centre and somewhere around 15 for dp. More still with a decent manifold.

StickyMicky

is the nurspec actualy made to give more power or is it just noise?

StickyMicky

john, try and get sumbody with a revolution exhaust to take you for a run and see how it fares, i did notice extra noise over standerd, but its nothing quite as harsh as ive heard with other scoobys exhausts

from memory i think jetex make the revolution systems, and jetex pride themselves on being "the quiet preformer"

Mad Scientist

But you have to admit that the noise is wicked! I'd take the noise anyday........i'd even be prepared to lose 9bhp for the noise! Can't beat it on a Summers evening with the windows open!!!!

Pavlo

My Hayward and scott exhaust is perfectly sociable. with resonated centre, and their traditional back box, 3" throughout

Paul

john banks

StickyMicky, I already have a 3" Revolution exhaust on mine, getting it welded up to sort the leaking slip joints, I still think it is a bit loud, but AlanG has had success with a silencer he had put in the centre section, so I need to hear his.

sammyh

iTrader: (1)

Nur spec with a bung - job done

MorayMackenzie

I guess I could try fitting an STI backbox... _inside_ the Pat spec system on the car.

StickyMicky

john do u have a decat downpipe on yours?

T-uk

Yes he does. I think the revolution system is guff because of poor downpipe design (wastegate flow leading to boost creep on some turbos) and crap slip joints.

Fangoria

iTrader: (1)

With The Gruppes headers the car would sound completely different anyway

No more complaints from the neighbours as the car is a lot quieter..........

Whats wrong with a combination like HKS Hiper and Gruppe S - thats fairly quiet isnt it?? - several db's quieter than a ridiculous BPM or other variant!!!

Errr doesnt putting the Bung in really restrict the power - the HKS can drive like a dog with the bung in! - so cant see the Blitz being hugely different

Surprised at the small power difference

john banks

I still think the Blitz is too loud with a resonated centre section and headers on. I think the Revolution is pretty noisy too. If you are getting a big power gain maybe it is worth it, but that doesn't seem to be the case.

paul_davies

The revoloution cat back system is very quiet, however I have recently fitted the downpipe and the noise has increased significantly along woth the power, the revoloution DP and system is supposed to be worth 39BHP? I'll find out if I make my way off of Pele's reserve list!!

7 Foot

Sorry JB, having never met you I thought you were about 45.

Sorry mate!!!!

john banks

I'm 29 Why does everyone think I'm an old fart ?

[Edited by john banks - 10/31/2003 8:22:58 PM]

7 Foot

Coz unlik mosed peepol on heer yoo can spell your wize words so wel.

Nice edit BTW

hades

Would be interesting to see if some of the quiet but high flow type backboxes will get very close to the Blitz for power - e.g. prodrive, remus etc. Agree that that downpipe makes most difference to power, backbox makes most difference to noise, and have even recommended to people looking for a more "stealth" mod to change the whole exhaust except the backbox.

John: it must be your age. Just over a year ago I was off looking for fairly quiet but high flow system (ended up with full APS system, suits me fine). Am 30 now, so it all fits ...

Andy.F

M5 speak

David_Wallis

John, I know what your saying about 20mins in the car.. ask p20spd, pavlo, pat etc how loud mine is..

Custom Headers, 2 -- Yes TWO up-pipes..
Home made mild steel 3" D/Pipe, External W/Gate - No silencer.. HKS Hiper. = Noisy!

David

Fangoria

iTrader: (1)

Did someone say 39bhp from an exhaust change.....

Thought the average was 10-20bhp

John - just buy a second car like a sh*tsubishi - they are a fair bit quieter in standard trim - may be a bit slow though (if the Evo 8 is anything to go by!)

although at the young age of 29 you may struggle with the wee insurance

paul_davies

The revoloution complete system (downpipe, center and backbox)claims a measured 39BHP on their sti v4?

Fangoria

iTrader: (1)

probably on a very cold day, with good fuel and very optimistic rollers!

X SOOOBY

i am 41 and still love the noise allthough my 17 year old son wants more noise

Alberick

john,

I had the Blitz Nur Spec R on my 99 Turbo and after having the car dyno'ed with Blitz and with standard "twin pea shooter", the difference in torque & power was so minimal, that the noise of the Nur spec R was not worth it.

315.7 NM @ 3990 rpm
177.9 Kw @ 5710 rpm

Can't remember what he values were with the OEM exhaust on, but I remember that power was slightly less and torque was improved with the pea shooter.

I often hear people rave about how the car goes after fitting an exhaust and d/p but I wonder if this is not the impression the car gives when making all that noise....
As for me I sold the Nur Spec R and bought an STI backbox (not the standard one, the STI aftermarket one with the 120mm tail) just for the looks.