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Discussion Starter #1
Hello, Members.
How are you?

I have 15 STi and Planning to Dyno tune upcoming summer.

So Far Installed
275.30R19 +50mm A/S 3+
255 40R18 +55mm WP72
K&N Air Filter - Stock Box
IAG AOS Street
Reverse Coolant mod
Redline 5w30
Mazda Oil Filter N3R1-14-302 (Correct BPV)
Corsa Cat Back
94 Octane

Planning
aFE Downpipe
Cobb Accessport
TGV Delete

Maybe
Bigger Injector
Bigger TMIC

Here are my Questions.

anyone has experience with aFE Downpipe?
I picked it because it's not 3inch, it's 2.5 and I don't plan to be loud loud or crazy power. (not bought yet)
Is there other 2.5inch downpipe close to factory but better flow?
Is factory downpipe that restrictive?
Do I need heat shield for aFE Downpipe?

I guess depends on local tuner, I am thinking 90oct and 93 oct tune mapped to Si-drive, is it possible? (90 int, 90 sport, 93 sport#)

Anything I should consider or missing out?

Thanks.
58713
 

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Hmm, a little more details please....

the aFE downpipe you mention...is it catted, or catless? Unless it's a "high flow cat" on the aFE downpipe, i don't see how a catted version would be any different than stock (except maybe the mouth). Of course, catless 2.5" downpipe will flow wayyy better (not speaking to the unburnt HC's). even then , a high flow cat would likely be a marginal boost in available efficiency.

IMO, going to a 3" downpipe doesn't necessarily make it loud loud, and unless you're chasing it, the tune you get with a 3" aftermarket downpipe (even catted) can be focused more for response than necessarily outright power. Interview your tuner, and let them know what you are looking for.

Having said that, yes, Going to a 3" downpipe will make the exhaust comparitively louder, but i think the type of exhaust will shape the volume, and type of sound, that your exhaust will make.

without knowing more, i think a 3" downpipe (I prefer catted) is a nice step up in response (!) and power.
 

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Discussion Starter #3
Thanks for the Reply CHESTYC

aFE was Catted. It said improve flow. not high flow.
Cobb or aFE both does not have data with how much flow increase.
I dont ever plan to go catless.

I plan to take STi to my home country which exhaust loudness is strict or more than Californica.
If it's not louder than Veloster N. then hopfully pass the inspection.

Cobb + Corsa any drone to excpect??? do you know?

Thanks.
 

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Hello, Planning aFE Downpipe

Here are my Questions.

anyone has experience with aFE Downpipe?
I picked it because it's not 3inch, it's 2.5 and I don't plan to be loud loud or crazy power. (not bought yet)
Is there other 2.5inch downpipe close to factory but better flow?
Is factory downpipe that restrictive?
Do I need heat shield for aFE Downpipe?
Are your sure about the dia? Look at the neck-down to mate with the stock exhaust Surely it's 3" to 2.5"

58726



There are other 3" DPs avaialable. Start with Cobb, ETS, Invidia . . .
 

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I agree with the above. I dont know if there are other 2.5" dp's out there but its just not worth it. The factory dp is so restrictive so i dont see why anyone would want something only a "little better" I think your best bet is to go for a 3" or not at all. If your worried about sound, you could always keep the stock exhaust and just get one of those down pipe adapters. Another option would be to get a real quiet exhaust like the Miltek if its offered for your car. Ive herd Miltek is as quiet as it gets, and its also a 3"
 

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I third the last two posts - almost wrote the same . . .
 

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I agree with the above. I dont know if there are other 2.5" dp's out there but its just not worth it. The factory dp is so restrictive so i dont see why anyone would want something only a "little better" I think your best bet is to go for a 3" or not at all. If your worried about sound, you could always keep the stock exhaust and just get one of those down pipe adapters. Another option would be to get a real quiet exhaust like the Miltek if its offered for your car. Ive herd Miltek is as quiet as it gets, and its also a 3"
Agreed. Milltek is as quiet as it gets next to the stock exhaust.

They also make a resonated & catted downpipe, however, it's very expensive and possibly discontinued..

Here's an example of Milltek's turboback exhaust.. talk about quiet. Most reviews say that it's almost as quiet as the stock exhaust, but without the boominess. I've seen 0 complaints of drone.

 

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Cobb is not quiet. They aim for what many companies do for their quieter performance exhausts. Barely legal/tolerable. Yes there are many far louder, but Cobb is not generally not near stock. I mostly familiar with older Cobb, but I don't believe their market or goals have changed.
 

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Very few exhaust are stock quiet. The COBB turbo back is very middle of the road loudness wise IMHO.

Cobb is not quiet. They aim for what many companies do for their quieter performance exhausts. Barely legal/tolerable. Yes there are many far louder, but Cobb is not generally not near stock. I mostly familiar with older Cobb, but I don't believe their market or goals have changed.
 
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