Well I will be starting on the TC install in a few weeks but I was curious to find out some info on the 3 in cutout. I decide to get this because I don't have the funds to build a 3 in exhaust at the moment, I purchased this from summitracing:

Now my question is :

1. Ideally where should I place this, I've seen some place it on the downpipe before the tranny while others further down the exhaust. I was thinking placing where my cat is that way I will have a test/open exhaust, kills two birds with one stone. When emissions rolls around.I can put my cat back in. Would this work?

2. How does running a cutout affect the o2 sensor after the cat? Would it throw a code? make it run lean?

 

The O2 sensor behind the cat has no bearings on your a/f ratio. Guys with test pipes sometimes throw codes once in a while for that rear sensor, but it seems to be sporadic. It may work the way you're describing it, but it may not fit.

 

I can't say for certain but I assume it'd throw a code. I think it's inevitable that you will be throwing codes anyways with a turbo on your car, so to me at least, it is not even worth discussing.

About placement, the test pipe area is a good way to kill 2 birds with one stone. But the less backpressure you have the more your turbo will like you, so the closer it is to the turbo the better it will be for performance. The other consideration you have to account for is where you'll be installing your wideband (you are going to install a wideband, right?). Remember that if you put this upstream of your wideband, i.e. closer to your turbo than your wideband is, then any wideband readings you get with the cutout open will be useless. This is how I30tMikeD's is set up (when we put my wideband on his car it is in the place of the stock after-cat wideband), but since his cutout is way up towards the front of the car, we can't get any useful wideband readings when we open up his cutout.

 

One problem that I think guys have ran into trying to put a cut out in place of the stock cat is clearance. There is not much side to side in that particular spot. I would try and put it closer to the turbo, but like neal said you will want to make sure you have the wide band bung placed before the cut out if you do indeed get one.

Having a cut out is great. 3" exhaust can be really loud on a day to day basis. With my cut out closed my car is very quiet, can't really hear much till my waste gate opens.

 

I put mine right before the cat, so as to stay somewhat emissions legal. With it open, I hit 1-2psi more boost than with it closed.

 

Just to add, I have had my rear (cat) o2 sensor disconnected and zip tied under my car for the last 9 months with no CEL. When I run my JWT ECU I actually have no CEL's....That was kinda my goal, to have a 350whp I30 that still feels fairly stock on a day to day basis, can still pass emissions, and run 12's at the track.

 

The reason I wanted to place the cat other than mention above is the fact that I don't want to cut up Mingo's downpipe pipe but if it is benificial than it is what I will do. I knew that the wideband will have to go before the cutout to ensure a correct reading. Thanx for the help guys.

 

With the O2 sensor, how far away should be from the turbo? If I was to put the cutout on the downpipe just before the tranny, and the wideband a few inches upstream from there (a foot to foot and a half from the turbo) would it still be too close?

 

Do you guys angle that open portion of the cutout straight down or more to the side? How about clearance issues?

 

[/QUOTE][QUOTE]The O2 sensor behind the cat has no bearings on your a/f ratio. Guys with test pipes sometimes throw codes once in a while for that rear sensor, but it seems to be sporadic. It may work the way you're describing it, but it may not fit.

i have a test pipe and was able to keep my o2 sensor.

 

you can use the boost actuated cuttout made by ATP performance. I have it and it is relatively compact and there are numerouse ways to position it

 

With a turbocharged car the boost activated cutout would annoy me to no end. With a supercharged car boost is controlled by RPM so it's predictable, but with a turbocharged car boost is controlled by load, which means that pretty much any time you floor your car it would open, even when you don't want it to.

 

Thought about it but $30 compare to over $200. I would rather get a true 3 in exhaust...

 

true true, i forget you guys build full boost alot quicker than i do

 

WHERE?????? lol, where is the website for this? i want this... phone number? website? im googling....

 

www.atpturbo.com

 

couldnt find the one chris was talking about, is there a direct purchase link somewhere or description on it?

 

nevermind, i found it

 

chris where did u put ure cutout? any pics of it installed? and i want to run a wideband set up....if i get this i wont need a straight pipe or catback anymore...muhahaa, beautiful...

 

Just make sure the o2 is upstream from the cutout, that would ensure am accurate reading. With that electric or boost driven cutout, since its smaller(unlike mine) you can put near the cat area without clearance issues...