Apexi N1 Exhaust system... now what?...

[DSMnOOb00]

SO I got this Apexi system for dirt cheap! it has the cat , the pipeing from the cat and the muffler... all 3inch... but now it looks like I need a 3inch downpipe... plus I was reading other posting, and I guess I also need a 3"inch 02 houseing? but I cant find any on ebay... so what is it exactly what I need to make this happen?

Thanks!

 

[1992awdlaser]

You don't need an aftermarket o2 housing with most 3" downpipes.

 

[DSMnOOb00]

I dont understand... from the turbo to the downpipe, it looks like its only 2.5, but all my aftermarket pipes are 3inch... so what am I missing?

 

[DSM4me44]

Nothing. You don't need a new 02 housing. They don't match on most exhaust systems, until eventually you decided to get a new one. Not that big of a deal having the stock 02 for now.

 

[DSMnOOb00]

Well then how I am going to install my new exhaust system? so this what what I dont understand...

Turbo->>02 houseing 2.5INCH-->>Downpipe 3INCH->>CAT3INCH->>PIPE3inch->> MUFFLER3inch to 4.5inch....

where the houseing meets the downpipe, if my downpipe is 3inches and my houseing is 2.5 will I need to get a 3inch houseing.... I just wana make sure, some people are saying that my downpipe might just bolt stright up to my turbo..

O2 Sensor Housing
In between the turbo and the downpipe is a 90 degree elbow called the O2 Sensor Housing. The O2 sensor screws into this housing. This is the last restriction in the exhaust system. The stock unit can be ported out, or you can simply buy a better flowing unit. If you choose to go with a "turbo-back" exhaust system, this housing will automatically be replaced

 

[Jordanbutter]

You'd have to be getting a special down pipe that is an O2 and down pipe all in one (ideal for turbo back systems). You can port the stock O2 and that will make it larger. Also you wont have bolt problems they should be in the same spot the only difference is the hole on the housing is .5in smaller than the downpipe.

 

[gsxeclipse97]

You have a 50 trim on your car? I'm assuming thats a 255 fuel pump. Do you have a fpr or anything. From your list I don't see any of the basic things that you would need to even suport

The point of that is i would be a little worried about running those 2 imtems by themselves with out any method of tuning you would be dumping way to much fuel.. and no boost controller also. If you install the exhaust you may encounter some severe boost spikes is you are just running the turbo with no method to controll it.

 

[housegsx]

Most downpipes I've seen are 2.5 inch where they meet the o2 housing and then expand to 3 inch after the flex section to bolt directly to a 3 inch cat or your catback exhaust system.

 

[welfle18]

i have the 3" full apexi n1 exhaust and it will bolt right up to the factory o2 housing with no problems.

 

[wvturbo2]

The one I have and others I've seen are 3 inch until a couple inches from the flange to the 02 they go down to 2.5 and fit the dp to the 02.

 

[Glliw]

Yes, the APEXI N1 downpipe is 2.5" before the flex section. Yes, The APEXI N1 downpipe will bolt up to stock o2 housing.

 

[SinEclipse]

I have the same exhaust and I got the Apexi DP along with it. The dp start as 2.5 then after the flex it becomes a full 3". Just get the right DP and it will bolt on without any problem.

 

[Zmann42087]

Just get the Road/Race Downpipe. It will fit perfectly between your stock O2 housing and the Apexi N1 cat-back.

 

[kmoore]

Just get the Road/Race Downpipe. It will fit perfectly between your stock O2 housing and the Apexi N1 cat-back.

+1 BIG TIME. Love my downpipe. And just an FYI... Your Apexi N1 is NOT a true 3".

 

[gsxeclipse97]

That is true if you own a gst but if you have a gsx it is 3 inches i posted the measurements from the web site and did the conversion from mm to inches. The gsx down pipe is 3 after the flex section and the exhaust is also 3 and expands to almost 31/4 at the rear. and the outlet is 4in. So long as you have a gsx your good to go

there here somewhere on another exhaust thread..

 

[kmoore]

Have you actually measured the exhaust YOURSELF with a tape measure? Mine was about 2.7"

 

[tkelly27]

Use calipers, they are super cheap nowadays.

Most downpipes go from 2.5" to 3", it's not a huge deal to have a small segment of 2.5" pipe. You would have to go with a tubular O2 housing (or a stock one that's been hogged out) and a DP that's been made for 3" at that flange to get anything different. I'm not sure if any brand has anything like that.

BTW, if you really want a true 3" down pipe, it's not incredibly hard or expensive to make. You could probably even get an exhaust shop to make it for you if you brought the parts in and had a cat on it.

 

[dsm-onster]

Most shops have a crush bender not a mandrel bender. even 2 cruch bent 45 degree angles significantly crush down the diameter of 3 inch pipe. buy a mandrel bent 90 and take it to a muffler shop and they can do the rest.

O2 Sensor Housing
In between the turbo and the downpipe is a 90 degree elbow called the O2 Sensor Housing. The O2 sensor screws into this housing. This is the last restriction in the exhaust system. The stock unit can be ported out, or you can simply buy a better flowing unit. If you choose to go with a "turbo-back" exhaust system, this housing will automatically be replaced

Usually, the term "turbo-back" refers to a system that bolts on to the stock o2 housing. . .

Yes, your o2 housing is the last un-modified restriction in a "turbo-back" upgrade exhaust system. But, many are happy with just using the stock 2g housing (you have one already).

Yes, you will see gains from replacing your stock o2 housing. But a 3inch bolt on downpipe is just that. It will bolt on to a stock o2 housing. And is still an excellent upgrade, even with a smaller 1G o2 housing. . .

 

[RedEyeBanDiT]

i havea 3 inch turbobak on stock housing, with no supporting upgrades, i get boost creep on the highway while hammerin down and it will hit 20psi and fuel cut

 

[dsm-onster]

i get boost creep on the highway while hammerin down and it will hit 20psi and fuel cut

Yep. This indicates that your stock o2 housing and exhaust upgrade is doing its job and freeing up flow quite well.

To fix the creap you really need to modify the wastegate flapper hole.

 

[talonalex92]

im not sure where this thread is even going any more, but none the less, i have a 3'' slowboy down pipe. It will bolt to the stock o2 housing, it will bolt to any o2 housing since the bolts to hold it to it are adjustable left and right. I now have a 3'' o2 housing (ebay). Zero boost creep, zero problems.

 

[gsxeclipse97]

Have you actually measured the exhaust YOURSELF with a tape measure? Mine was about 2.7"

Yep It was 3 right on the dot.

 

[DSMnOOb00]

im not sure where this thread is even going any more, but none the less, i have a 3'' slowboy down pipe. It will bolt to the stock o2 housing, it will bolt to any o2 housing since the bolts to hold it to it are adjustable left and right. I now have a 3'' o2 housing (ebay). Zero boost creep, zero problems.

You got one off ebay? I cant seem to find one there...

 

[RedTurboEclipse]

Those crazy roadrace guys, they have never recommended the APEXi downpipe since back in the day..

http://roadraceengineering.com/parts/apex/apexdp-installed.jpg
http://roadraceengineering.com/parts/apex/apexdp-sharpchange.jpg

RRE's downpipe flexpipe compared to apexi's
http://roadraceengineering.com/parts/apex/apexdp-shortflex.jpg

http://roadraceengineering.com/parts/apex/apexdp-boltholewrong.jpg
http://roadraceengineering.com/parts/apex/apexdp-smallinsideflex.jpg
http://roadraceengineering.com/parts/apex/apexdp-tabgonnabreak.jpg
http://roadraceengineering.com/parts/apex/apexdp-wontfitfake3inchexh.jpg

 

[talonalex92]

You got one off ebay? I cant seem to find one there...

they're fairly easy to find, try just searching something like "Dsm o2 housing; DSM dump; Dsm turbo outlet". Just make sure to search the title and description, you will have better results. Good luck!