You're looking for a real quiet exhaust, so keeping that section 2.5" may not be a bad idea. I'll trust your judgment on the sound as you've been very picky thus far.

 

The Borla C/B for my old STi necked down to 2.5-so that it bolts to factory cat.The Cobb catted D/P necked down to 2.5.According to Cobb this neck down is good to 450HP before it starts to be restrictive.
That's why they did it like that. So a customer can bolt the thing right on using basic hand tools.The UICP in the factory neck down is probably more of a power robbing part.

 

The turbo compressor outlet is that size anyway... a bottleneck is something that is smaller than anything between point A and B. That transition is not.

Take the combined area of the wastegate port and the turbine outlet. I bet it's way less than the cross sectional area of the 2.5" OD piece of exhaust. So it's not really that much of a restriction, but the transition from 3", to 2.5", back to 3" would cause turbulence.

This is assuming you're talking about the stock turbo

 

preliminary results are in!

initial impressions are very favorable. MUCH quieter than buschur's "quiet" exhaust. the quality is great, and it's pretty light, despite a good-sized canister in the back. idle is slightly louder than stock (try to grumble to yourself when you're hanging out outside, it's pretty close ), and it's not that much louder on throttle either. flat out, it actually gets drowned out by my engine noise.

those that haven't seen magnaflow's demo vid: http://videos.streetfire.net/video/1...i-X_318525.htm

the video is actually very accurate to what i hear, just crank the volume up a bit so it's clearly audible, but not loud enough to disturb anyone nearby you. it's surprisingly close to what i had before with the world sport 2, but with a bit more growl to it.

huge for value and quiet performance. it's unexpected from magnaflow for sure, but to me, it's definitely a winner. i was planning to weld in some bottle type resonators in case it gets too loud, but it's what i expected, so i'm only going to take care of that 2.5" pinch and call it a day.

and of significant note, it doesn't come with any gaskets, so if you have a 3" pipe for the cat already, make sure you have a 3" gasket as well.

 

No pics?

So it bottles up from 3" to 2.5" at the cat? Correct?

 

i will have pics tonight, didn't bring my camera with me (i snuck out of work to borrow a buddy's lift )

and yeah the flange that meets the cat pipe pinches at 2.5. if you didn't upgrade the cat pipe it'd match perfectly. since i have a 3" cat pipe, it goes 3" to 2.5" to 3". it might be just my butt dyno, but i kind of feel like it's not picking up speed as fast. again, "feel" is just my opinion, no hard evidence. i'm gonna open up that 2.5 bottleneck anyway, just because i can.

 

Sounds like a winner for the price.

 

Where are the rest of the pics? I anxious to see what it will look like mounted up close up.

 

if anyone need more pics, just ask. my photography skills are fayle, so be warned

and a short vid clip of idle and rev: http://www.youtube.com/watch?v=QqnYwCfwCfQ

i can tell you that the volume in the clip is not an exact representation, but there's no other way for me to correctly tell you how loud it is other than in person, so you'll have to take my word for it that it's only slightly louder than stock. it's "quiet" compared to most other options out there, but as you can tell at least, it still growls. it's quiet enough so my 60+ year old neighbors didn't complain when i drove back and forth several times, whereas they flipped over my buschur "quiet" exhaust.

 

Impressed, I think it sounds great.Thanx for making/posting the vid you made.
It looks like it fits like a glove,it's tucked up,not hanging low. Smooth bends and simple design is what I like. I like the tuned but muted tone.Must sound alot better under WOT

Def on the top of my list for C/B's and priced nice too.

 

Man thats looks **** and sounds good low deep tone just what Im lookin for. I cant wait till mine finally comes in

 

Looks good, sounds good, nice and mellow... I'm sold.

I think it sounds about perfect with the test pipe and full DP. Thanks for making that video.

 

update...it failed my, um, "mom" test

apparently it drones a bit on high speed (especially if you're a gsr) above 3500rpm (which is about 70mph on gsr's 5th gear) for the rear passengers. if you have an mr, this won't be a problem because your 6th gear would make the droning non-existent. this is probably contributed to the lack of a resonator in the pipes.

i'm going to add two (! ) resonators into the piping by this weekend, and should eliminate the droning altogether.

 

First impressions are is sounds close enough to stock I probably wouldn't get it for that.

I think the best reason to get this is for the looks. It looks 1000 times better than the factory welded on crappy tip and sounds only a tiny bit louder. A good conservative choice for a DD for sure!

 

Well I finally installed my exhaust today. I must say its not much louder than stock which is good in a way its less attention,but when you go WOT it sounds pretty mean almost like a jet I guessin the turbo is breathing better thats why.If anybody is looking for a cheap,quiet,quality exhaust this is your ticket.