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so i have a downpipe from my 05 that my local exhaust guy is going to help me to fit it to the 08, my question is, is it alright to run a downpipe on the 08's without engine management. i heard when the 06's came out that due to the 2.5l they had boost spike but that was normally catless. i plan to run a high flow cat also. anyone running one? i am going to get a full custom tune as soon as the tactrix cables come out for the 08's..should i have it made and wait to put it on or what?
 

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Are you going to keep the stock exhaust on? With the high flow cat I don't think that you will have any problems.
 

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Discussion Starter #4
ill probably mimic the turboxs stealth back and run 3in all the way to the axelback. i think im going to go ahead and do it
 

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so i have a downpipe from my 05 that my local exhaust guy is going to help me to fit it to the 08, my question is, is it alright to run a downpipe on the 08's without engine management. i heard when the 06's came out that due to the 2.5l they had boost spike but that was normally catless. i plan to run a high flow cat also. anyone running one? i am going to get a full custom tune as soon as the tactrix cables come out for the 08's..should i have it made and wait to put it on or what?
No worries. It will run OK. You will get an occasional CEL for over boost or running lean. No worries just clear the code.

A stock map with full exhaust is not optimal performance, but you will not damage the car, or have any major issues.

Sean S.

www.RalliTEK.com

 

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I have been running the UR downpipe for two weeks with high flow cat and stock exhaust with resonator removed and I don't baby my car at all, it runs just fine. No CEL can't feel any boost creep and assume there isnt a spike as I get no CEL so I would say go for it and no worries. It is amazing how much better it feels with a freed up DP.

Seth
 

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i have had the Invidia 3" catless DP for 3 weeks, and i have had my CEL, Traction, and Cruise lights on. Plus with my BOV my car back fires.
 

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The catless dp will burn up the O2 sensor back there. You need to get a CEL fix for the DP. Those lights mean that you have probably been overboosting, you need to reset the ECU. The backfiring is actually gas burning in the exhaust cause the Air Fuel Ratio is going rich when you shift cause you are not recirculating. I would recommend going with the Cobb AP to help correct that, also a boost controller would help with any overboosting.
 

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The catless dp will burn up the O2 sensor back there. You need to get a CEL fix for the DP. Those lights mean that you have probably been overboosting, you need to reset the ECU. The backfiring is actually gas burning in the exhaust cause the Air Fuel Ratio is going rich when you shift cause you are not recirculating. I would recommend going with the Cobb AP to help correct that, also a boost controller would help with any overboosting.
yeah i know what it is. i jus needa put that Tru Boost on lol. plus its not that big of deal right now, i can drive it without it backfiring, its only when i am lazy with my shift it does it.
 

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The catless dp will burn up the O2 sensor back there. You need to get a CEL fix for the DP. Those lights mean that you have probably been overboosting, you need to reset the ECU. The backfiring is actually gas burning in the exhaust cause the Air Fuel Ratio is going rich when you shift cause you are not recirculating. I would recommend going with the Cobb AP to help correct that, also a boost controller would help with any overboosting.

Exactly!

-Sean S.

www.RalliTEK.com

Here is a link to a CEL Boss for your rear O2 sensor...

http://www.rallitek.com/rao2sesp.html

 

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Discussion Starter #12
luckily i have a celfix already in my old one...im going to do it the weekend of valentines day when i go home so ill let everyone know how it goes and possibly take pics while im under there
 

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You shouldn't have any problems. It is like a new car with the downpipe installed. Can't wait to get a CAI and AP should be even better. Specially when I get out of the mountains.

Seth
 

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You shouldn't have any problems. It is like a new car with the downpipe installed. Can't wait to get a CAI and AP should be even better. Specially when I get out of the mountains.

Seth
Seth,

You will love the difference the AP will make. Tuning makes a HUGE difference! Especially with a ProTune map. I am running our RalliTEK Stg2 ProTune on my car. Dramatic difference. Let me know when you are ready for an AP. I'll send you our Stg2 map. I can custom it for whatever intake you want to use.

Thanks,

Sean S.

www.RalliTEK.com

 

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Cool thanks Sean. I was looking at the AVO intake as well. I am on hold for a couple of months till we get moved to South Carolina and get settled. Once that happens I will give you a call and have you customize it for the AVO intake and UR downpipe. Would installing the AVO TMIC require a map too? Thanks.

Seth
 

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Cool thanks Sean. I was looking at the AVO intake as well. I am on hold for a couple of months till we get moved to South Carolina and get settled. Once that happens I will give you a call and have you customize it for the AVO intake and UR downpipe. Would installing the AVO TMIC require a map too? Thanks.

Seth

Seth,

Intercooler will not require mapping, you can bolt-on and go!

Thanks,

Sean S.

www.RalliTEK.com

 

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Sean,
What about if you go to FMIC? Do you need to tune then?
With the extra air volume of a FMIC tune is not required, but turbo/throttle response (lag) can be improved, and ignition timing can be more aggressive due to the cooler/more consistent temperatures. TMIC does not increase lag, so not needed. Larger TMIC can allow for a bit more aggressive settings if desired.

Thanks!

Sean S.

www.RalliTEK.com

 

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So far this thread has been really helpful. I'm thinking about buying a catless Invidia bellmouth downpipe in the near future. I plan on a tune, but it might not be for a month or so after I'm able to get the downpipe. I'm REAL worried about any problems.

So is it safe to drive the car somewhat aggressively if you aren't tuned? I plan on keeping the stock BOV, and possibly getting the resistor CEL fix as an interim solution.

It's either this or suspension....so we'll see. lol.
 

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I am stock except for an exhaust delete (just a straight pipe past the axle)

friend offered me an invidia DP from his 08 WRX he traded in for a Forester

I'll probably get a tune but it won't be for a while since AP = $$$

am I right in assuming I'll be fine as long as I don't remove any more cats or resonators?
 
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