As a general question, does it really matter what type of downpipe do you get in the 3inch world? Divorced vs Bellmouth? Catted vs non catted would be personal preference but Im going to be running e85 anyways so the cataylic converter is not an issue.
The issue is whether getting a no name brand downpipe vs named brand?
If they are all 3 inch, whats the big difference?
Metal fabrication?
Longigetivity?
Any helpful advice will be greatly appreciated.

 

Doesn't really matter as long as it's not flat plate (unless you're running EWG) and it's a name brand part.

You don't even need 3" for 95% of setups.

 

Whats a flat plate?
What if you would want to run an EWG setup later on?
Also, would the material of metal be ok to install an openining right after the 02 sensor that would be electronically controlled? I forgot what theyre called.

 

There is no definitive evidence that states whether divorced or bellmouth is better. Stick with invidia catless for a good and cheap option, it's what I'm running. I haven't heard any bad things about downpipes from the various major brands (Cobb, Perrin, invidia, grimmspeed etc)

 

1.


2. Then any will work, but depending on the make you might have trouble fitting a divorced.

3. 100% of cutouts fail prematurely. 100%.

 

Cool thanks bro.

 

Just curious to why the flat plate is no good? The downpipe Faq on the other site says

There is no irrefutable evidence that one design is better than the other. The thought process is that the greater the separation there is between the wastegate gases and exhaust gases, the smoother the overall exhaust flow.

 

I think they're talking about going aftermarket, at least 3"...

 

Because it blocks the flow of the wastegate and creates a lot of turbulence right behind the turbo. It can impede the ability of air to get past the turbo and can potentially reduce spool speed and create boost creep because air can't escape fast enough.

And to refute the 3" claiming, many exhausts are actually 2.5", Cobb for example. SPT makes 2.5" catback. And there are a few others. I'm making 400 whp on a 2.5" exhaust though at my point it's a restriction, though it's partially alleviated by the fact that I have an EWG. For a lightly modded car, 2.5 or 3" will work.

 

Thanks for the answer im running the HKS (catless)with the plateon my02, was going to do a EWG but have decided to move onto a newer model wrx in a few months and will make sure to go with another design.