My GT 3.2L exhaust upgrades - with vid links - Alfa Romeo Forum
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(Post Link) post #1 of 12 Old 12-05-09 Thread Starter
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My GT 3.2L exhaust upgrades - with vid links

thought i'd share my latest exhaust mod. i have a 3.2L GT, and quite a while ago i changed just the backbox/rear muffler for a brand called Mille Miglia. this is a brand local to me, in Australia, built by HiTech Mufflers in Sydney, who are well renowned over here, and produce many excellent products for a host of exotic cars including Fezzas and Lambos, etc. they also deliver overseas, so they are an option for anyone.

their website does not list specific GT products, but most are shared with the 156GTA. note they have improved the cat design compared with the website photo; see my pic below. btw, 'ring' them, rather than email, because i don't think they read emails often!

Mille Miglia - Porsche and Ferrari Performance Exhausts

the backbox cost AUS$1050 a couple years ago. could be a bit more now. nice polished stainless steel and very high build quality. much louder and 'bassier' than factory, and sounded very good. but it does drone at around 2000rpm 'under load'; but is very quiet when cruising.

just last week, i bought their high flow catalytic converters, AUS$1550. these feature two high flow 200-cell metal 2.5" cats made by Catco. overall build quality is good, but not fantastic; bits of slag and blobs around the place. but the piping is completely 'straight' compared with the original. and the original cats are off-centre. fitment is no probs; straight forward swap-over, which i did myself at home.

sound:
*backbox alone: louder, deeper/growly/bassy
*backbox + high flow cats: same loudness, but additional higher frequencies, producing a more mechanical sound, that i really like

weights:
*backbox old:new = 11.5:8.6 kg (2.9kg weight loss)
*cats old:new = 7.5:4.9 kg (2.6kg weight loss)

power: car run on a local dyno, less than 2 weeks apart, before/after cat fitment
*backbox alone: 140.6kW/188.5hp at the wheels
*backbox + cats: 144.1kW/193.2hp

so, a bit of improvement in power (and also torque) right across the board. can i FEEL the difference? well, i honestly can't. the car drives just as well. but it sounds better.

*backbox pics:
http://pic20.picturetrail.com/VOL97/.../317356860.jpg
http://pic20.picturetrail.com/VOL97/.../318168305.jpg

*cats pic:
http://pic20.picturetrail.com/VOL97/.../363723378.jpg
http://pic20.picturetrail.com/VOL97/.../363723556.jpg

*videos:
YouTube - Alfa GT 3.2L Mille Miglia high flow cats + rear muffler (1)

YouTube - Alfa GT 3.2L Mille Miglia high flow cats + rear muffler (2)

YouTube - Alfa GT 3.2L Mille Miglia high flow cats + rear muffler (3)

i hope you like.


GT . 3.2 . Q2 . Kyalami Black - Red . Eibach . KONI . ASSO . ATP 19" . TAROX . FERODO . Mille Miglia exhaust
155 . 2.0 8V TS . Grigio Grey - Grey . H&R coilover . Enkei 17" . TAROX . GOODRIDGE . REMUS
75 . 3.0 . Alfa Red - Grey

Last edited by shiny_car; 12-05-09 at 11:28.
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Re: My GT 3.2L exhaust upgrades - with vid links

nice set up shiny, the backbox looks like a unicorse job.........sounds nice
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Re: My GT 3.2L exhaust upgrades - with vid links

Nice
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Re: My GT 3.2L exhaust upgrades - with vid links

Sounds great! Nice double declutch on the upshift, it's becoming a lost art that.
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(Post Link) post #5 of 12 Old 12-05-09 Thread Starter
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Re: My GT 3.2L exhaust upgrades - with vid links

i don't normally do that, or it can be habit and i don't realise it. unnecessary, but sounds good.

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Re: My GT 3.2L exhaust upgrades - with vid links

Truly beautiful sound. More importantly, it sounds right for the car.

Nice!
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Re: My GT 3.2L exhaust upgrades - with vid links

Nice one SC. sounds lovely, looks spot on too.
Bit random but.... Im listening to radio2 at mo and rianna's 'umbrella' is on and I was reading your post when she said 'shiny car' in the lyrics. Like i said, bit random, but still kind of relevant.
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Re: My GT 3.2L exhaust upgrades - with vid links

Sounds lovely
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Re: My GT 3.2L exhaust upgrades - with vid links

Sounds good, thanks for all the useful detail. Like the 19s, very stylish, and nice exhaust tones there. I wonder if you can feel any difference with throttle response? Would you expect any change of any characteristic over time?

Our GTs' have got 4 cats I believe, I would like to know if it would be possible to significantly increase throttle sensitivity without sacrificing an MOT Pass (I presume some decatting would be needed)?! Having to replace cat sections would be real pain, surely there's a way of engineering this...(better response, no emission problem?)
Don't know if you get that out there, you probably have something like an MOT to pass.

Cheers.

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Re: My GT 3.2L exhaust upgrades - with vid links

Sounds alot like the Supersprint, which is a good thing

Liking that. How long has it been on? Does it still need to bed in? If so, it'll get louder!
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(Post Link) post #11 of 12 Old 13-05-09 Thread Starter
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Re: My GT 3.2L exhaust upgrades - with vid links

thanks guys.

i've not heard a unicorse or full supersprint system in real life - only on short clips like mine. i think unicorse would be a higher pitch sound, cos my friend Abyss (with 156GTA) is going to start with their backbox cos he likes the higher pitch sound (a la Ferrari). mine might be more like supersprint, with a fair bit of low grumble/bass. not really sure though! would be great if it was possible to hear them side by side.

the backbox has been fitted for about 12 months now, so is well run-in. alone, it produces a lot of low down rumble, but also drone. i still like it a lot though. the cats are only new - less than a week, and about 200km so far - and they have improved the sound. i don't know if the effect of the cats (in terms of sound or performance) will alter with time. do you think i can expect that? probably not like the rear muffler which has a lot of packing/steel wool/fibreglass (or whatever!) inside.

Quote:
Originally Posted by AroadformyGT View Post
I wonder if you can feel any difference with throttle response? Would you expect any change of any characteristic over time?
i cannot feel any difference. or at least, nothing startling. i need to drive the car more, to try and appreciate if throttle response is a bit better or not.

from the dyno reading, and comparing 'before/after', i wouldn't expect much. there is improvement across the rev range, but small.

Quote:
Our GTs' have got 4 cats I believe, I would like to know if it would be possible to significantly increase throttle sensitivity without sacrificing an MOT Pass (I presume some decatting would be needed)?!
indeed, the cats attached to the manifolds are meant to be quite restrictive to gas flow. another Oz Alfista - ALFA_001 on AO, with a 147GTA - has recently fitted GTV manifolds (phase 1, pre-cat versions), with aftermarket equal-length front pipes (that are between the manifolds and main cats). he reports considerable 'seat of the pants' improvements. so the gains are there to be had. yet they are a much bigger job to fit; 'recommended' fitment involves removing the engine (!), though he managed without doing that, but still dismantling much of the front suspension and aircon piping, etc. but he hasn't found the 'sound' too pleasing so far, and is trying to modify the exhaust further downstream to improve it.

i'm pretty sure it would pass MOT, particularly with the engine warm. the manifold cats cater for cold start ups, to reduce emissions at this time. but the main under-car cats take care of the rest once they are warmed up.

not sure if it's possible or worth just 'punching out' the guts of the cats on the manifolds. but ultimately, some new equal-length manifolds like unicorse or supersprint would be the way to go. $$$

but for me, it's mostly about 'sound', less about power. so i think i have finished. ...maybe.

attached, is my dyno print out from yesterday (backbox + high flow cats fitted). it is impossible to draw much conclusion or do comparisons with other dynos though.

Attached Images
File Type: jpg 364098353.jpg (39.7 KB, 13 views)
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Re: My GT 3.2L exhaust upgrades - with vid links

quality looks first class and i like the raspier edge the sound has now...

hearing it under load it sounds really rich & clean . . awesome sound
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