Chris -

Good question. I'd been wondering the same thing. Anyone have any info?

And, welcome to I-Club.

Rupe

 

some people are on a budget and the downpipe/uppipe free up a lot of power. and then throw on the catback, which doesn't free up as much power as the previous.

people who can afford it all at once will get the turbo back with up pipe.

at least that's what i think.

 

Straight Turbo back = catback + downpipe

they're the same thing, just some people mix and match parts to create the turbo back, but all turbo backs are a catback and a downpipe.

uppipe is just an uppipe, it's before the turbo, so it's not in the TBE package.

 

A lot of down pipes come with the mid pipe but some dont, so if it doesnt come with a mid pipe you need the down pipe, mid pipe and the cat back to have a TBE.

 

Yep exactly, it's the catted pipe right before the turbo. The pipe that routes exhaust through the turbo, you remove that pipe and replace it with a catless one and you notice a whole lot better spool up. But if you get the STi like you said you might, that pipe does not have a cat it in stock.

WRX = 3 cats (2 in downpipe 1 in uppipe)
STi = 2 cats in downpipe

 

Yes. Click on this link to see a diagram of the intake and exhaust on a WRX https://www.i-club.com/forums/attach...chmentid=26009.

 

Yes the up-pipe has a cat for cold start emisions and does retrict flow to the turbo... just like any cat does. Replacing it enhances spool up time and increases flow. Keep in mind that many people have leak issues when replacing this, i know i did, that can be a pain to fix considering its location. Leaks at the up-pipe will rob you of prescious power. There are many types of DP's; the one your looking to get it a bellmouth or a seperator flow pipe that ports exhaust smoothly back into the main pipe. This eliminates turbulence from the wategate. This is the main reason most people shop for different DP's and also the reason why the prices vary so much. The DP also has 2 cats (i think) so by replacing that as well your removing 2 cats..... which is that much more flow.

Most people do as many bolt ons as possible not only becasue it's a cheap way to go ...especially if you install yourself but much of it should be done if your going to ultimatly do heavier modifications like the turbo and intercooler. Its also a good way to learn about the car and it's potential. I'm getting ready to do EcuTek in the next month and this should not only tune the car maximizing the cars potential but should also take advantage of my present modifications as well. Many people go right to the ECU with accessport or xede or somthing else. My preference was to do the basic boltons first...... i want to swap out the stock turbo and the IC....


Sorry for the long post...



-K

 

Hmm.. interesting. The diagram only shows one cat in the DP. I've seen many post where people said that there were two in the DP. Unless the diagram is wrong... which it doesnt seem to be considering that second cat is still on my car and i have an aftermarket DP and up-pipe.


-K

 

It is correct. Many people say they are both in the downpipe because a lot of downpipes have the mid pipe also (1 piece) but actually 1 is in the downpipe and one is in the mid pipe. Look at this downpipe made by cobb it has in 1 piece the dp and mp http://cobbtuning.com/wrx/power-i.html#s-downpipe. Here is a link to Vishnu, notice they sell a dp that doesnt include the mid pipe http://www.vishnutuning.com/parts_wrx.htm#exhaust.

 

if you do go w/ a turbo-back exhaust w/ cats, and then change the stock up-pipe with a catless one, will it pass emissions?

 

The upipe cat is only used for cold start emissions so as long as your state doesnt do a cold start emissions test the upipe will not cause you to fail the sniffer test. Depending on your states laws, that doesnt mean you wont fail the visual if the guy knows what he is looking at.

 

Cool - I'll have to talk to my shop about it.
Thanks.