Stage 2 supporting mods? Clearing up the confusion

From the Cobb Tunning website it is stated that a full turbo back exhaust is necessary before flashing to their stage 2 tune via the AP.

However when I was researching last week I came across some threads that I can't locate now saying that either a highflow cat down pipe or a test pipe would be sufficient and relieving back pressure to allow for a reliable stage 2 map to be run.

Since I have an 05 most people recommended that the Up pipe be either gutted or swapped out.

The thing is I am very satisfied with the stock exhaust note and want to keep the car as quiet as possible. At the same time I do want to go to stage 2 but just want to make sure I am buying the sufficient mods for it. I really dont want any CELs so thats why I want to go with the HFC downpipe.

This is the highflowcat downpipe that I am interested in purchasing

http://www.infamousperformance.net/servlet/the-291/CNT-Performance-Subaru-Legacy/Detail

Any other recommendations?

do I need any adaptor to attach it to the stock exhaust or will this just bolt right up?

I saw this so thats what got me thinking...

http://www.infamousperformance.net/servlet/the-393/3%22-Downpipe-to-Factory/Detail

Do I need any adaptor for the up pipe also?

http://www.infamousperformance.net/servlet/the-165/DC-Sports-Turbo-Up-dsh-Pipe/Detail

Thanks you all so much for your help I am very appreciative.

1. That downpipe will require that 3" adapter to mate to the stock exhaust. http://www.infamousperformance.net/servlet/the-393/3%22-Downpipe-to-Factory/Detail

2. That up-pipe does not require adapters but new factory gaskets is highly recommended whenever changing any turbo pipes. I personally prefer a solid uppipe without the flex section mainly because it can be just as dangerous as a cat in there over a period of time. Flex sections are notorious for leaking too....

3. The cobb AP maps disables the corresponding CEL's even if you get a catless dp.

thanks so much bmx045!!!

So if I install a solid up pipe and that high flow downpipe I should be safe to upload the stage 2 map from the AP on my car?

No need for a full catback exhaust other than sound right?

thx

One thing I noticed when I went Stage 2 with a Cobb OTS map was an overboost problem. With a highflow catted downpipe ONLY, I had very few problems. When I nailed it in 3rd gear on a cold morning, it would trip an overboost. Me not knowing why, I thought maybe it was an exhaust restriction so I added a catback hoping to make it flow more freely. When I added the SPT catback, I overboosted like crazy even during just a roll on. The only way to get rid of this was a pro-tune even after e-mails back and forth from Cobb.

If I had to do it over again, I would keep the stock exhaust and run with just the highflow catted DP. The stock exaust is efficient enough to run at stage two levels and keeps the car nice and quiet.

Thats what i figured.

Thank you.

One thing I noticed when I went Stage 2 with a Cobb OTS map was an overboost problem. With a highflow catted downpipe ONLY, I had very few problems. When I nailed it in 3rd gear on a cold morning, it would trip an overboost. Me not knowing why, I thought maybe it was an exhaust restriction so I added a catback hoping to make it flow more freely. When I added the SPT catback, I overboosted like crazy even during just a roll on. The only way to get rid of this was a pro-tune even after e-mails back and forth from Cobb.

 

If I had to do it over again, I would keep the stock exhaust and run with just the highflow catted DP. The stock exaust is efficient enough to run at stage two levels and keeps the car nice and quiet.

what do you mean by overboost? creeping higher than stock pressure? why is that a problem? does the tune not compensate for this or is stock fuel not enough for the boost you are seeing?

It means the boost would spike too far above it's setpoint. Spike and creep are two very different things. Spike can typically be tuned out very easily whereas creep is a little more difficult to tune around. Mine would spike up to 21psi with the OTS Cobb map and then the fuel would cut which felt like someone slamming on the brakes. The more I read and the more I talked with my tuner and people on this board, I found that the map itself needed to be changed(Protune). When my tuner had my car on the dyno, he said my engine appeared to "breath really well" attributing to my overboost problem.

When Cobb makes an OTS map, they are making it for the 'majority' of cars out there. Each engine/turbo is a little different however in the way they function. You can run an OTS map without any problems for years, but you can also run one for a week and blow your engine. That's why it's important IMHO to find a good tuner to help tweak the map for YOUR car.

So its been nearly a month since I finally got the invidia up pipe and cnt downpipe with the stage 2 map installed. I have to say its amazzzing phillyd, def recommend to do soon. It turns the car into a whole new beast performance wise. And as others have mentioned by just doing those 2 mods the exhaust note is perfect IMO. A deep rumble all the way through the RPMs and only gets slightly loud past 5k.

Thank you CapnJack for your input it is most helpful.

I haven't had the opportunity to get it professionally tuned/dyno'd yet. But keeping fingers crossed nothing blows in engine. If anything the car is running slightly rich so it should be safe. Anyone please feel free to chime in here, a pro tune would mostly just help me get more efficient power for my engine and maybe improve my fuel economy a bit...?

If I have gone a month already without a pro tune without any problems I should be fine from a safety stand point correct? Assuming I stay ontop of maintenance (full synthetic oil changes every 5K etc.) and use 93 octane fuel.

Thank y'all for all of the help!!!!

If I have gone a month already without a pro tune without any problems I should be fine from a safety stand point correct? Assuming I stay ontop of maintenance (full synthetic oil changes every 5K etc.) and use 93 octane fuel.

What is "without any problems"? You aren't seeing smoke come out of the engine bay, or you haven't observed knock events or hesitation?

While I don't have direct experience with Cobb OTS maps, I think you'll find mention of some users who experienced undesirable levels of knock with generic maps. The best course of action would be to collect some data and find out if your car is happy with the tune (i.e. no high load / rpm knock). If it is, then great -- you probably don't need to change anything unless you want a bit more power.

I had the same overboosting issue that a lot of people ran into with a Cobb OTS tune. Mine led to a separated endtank on my stock intercooler. When I upgraded, I went with an Infamous tune. Great tune, smooth power, 0s all across the knock correction table in learning view.

As long as you're happy with the tune and the data comes back within range, stick with it. A number of people have been running OTS maps for a lot of miles with no major issues.

shutterbc: yes I havent observed knock events or hesitation

I plan on collecting some data asap thank you for the advice

joeblow: thank you also I heard a lot of great things from infamous tune. I will look into the knock correction table and try to learn a lot more about data logging to see if I need a protune or not...

thanks again for everyones help, most appreciated.