How to Install Catless Uppipe (Invidia)

2005-06 Legacy GT's have a catalytic converter inside the up pipe before the turbo, replacing gets you ~10whp and might save your turbo. I think Subaru realized this too and in 07 LGT's came with a catless same as STI up pipe, instead they introduced an air pump to help the emissions.

 

GrimmSpeed did some awesome CFM testing of different up pipes. Catted up pipes flow 165 CFM, you can gut the stock one, very involved process and you run the risk left over material going into your turbo, airflow does improve by 50 CFM (216 total), which is still worse then OEM catless uppipe (at 245 CFM). GrimmSpeed's uppipe did 293 CFM, which is almost double the airflow of stock. Now Grimm's up pipe does have a flex pipe, which IMO are not needed and add turbulence, that plus the price is why I went with the Invidia uppipe.

 

Up pipe is install is not hard, but is also not easy as the downpipe install. It's just a very involved process where you have to remove the headers and the downpipe.

 

Gain access to the turbo and downpipe.

http://legacygt.com/forums/attachment.php?attachmentid=256715&stc=1&d=1507959986

http://legacygt.com/forums/attachment.php?attachmentid=256716&stc=1&d=1507959986

 

Remove the EGT sensor if you can, it will help you more easily pull out the up pipe. Mine was stuck thus I had to remove the uppipe as is, it was still doable, just bent the sensor.

http://legacygt.com/forums/attachment.php?attachmentid=256717&stc=1&d=1507959986

 

Mine was so stuck I couldn't get it off even with MAP heat while it was off the car.

http://legacygt.com/forums/attachment.php?attachmentid=256726&d=1507960024

 

Downpipe has a bolt that holds it under the car, but there is also a little bracket that catches it. This was a pain to work with, I ended up cutting the lip off so that I can push down the downpipe more.

http://legacygt.com/forums/attachment.php?attachmentid=256718&stc=1&d=1507960261

 

Remove the downpipe bolts. There is one downpipe bolt (one on the intercooler side) which was nearly impossible to break loose, just not enough room for a breaker bar and a wrench cuts your hands. Use a screw driver to force the downpipe off the turbo. This all is much easier if you just remove the downpipe all together and replace it with a new one. I don't know why Subaru thought it is a great idea to put two bolts right under the downpipe.

http://legacygt.com/forums/attachment.php?attachmentid=256719&stc=1&d=1507959986

 

 

Next is removing the header, first you need to drop the diaper and start removing the super rusty heat shields, to gain access to the nuts on the heads.

Unplug and unhook the O2 sensor from the engine! O2 sensors are very sensitive on these cars, I damaged mine by leaving the exhaust manifold hang on the O2 sensor wires!

http://legacygt.com/forums/attachment.php?attachmentid=256720&stc=1&d=1507959986

http://legacygt.com/forums/attachment.php?attachmentid=256721&stc=1&d=1507959986

 

Don't forget to unbolt the up pipe from the header too.

http://legacygt.com/forums/attachment.php?attachmentid=256722&stc=1&d=1507959986

 

Up Pipe removed:

http://legacygt.com/forums/attachment.php?attachmentid=256723&stc=1&d=1507959986

 

Grab it and pull it out

http://legacygt.com/forums/attachment.php?attachmentid=256724&stc=1&d=1507959986

 

Invidia vs OEM catted up pipe header end:

http://legacygt.com/forums/attachment.php?attachmentid=256725&stc=1&d=1507959986

 

OEM LGT uppipe entry is about 40mm

http://legacygt.com/forums/attachment.php?attachmentid=256728&stc=1&d=1507959986

 

STI Uppipe is not much abetter at about 43mm

http://legacygt.com/forums/attachment.php?attachmentid=256729&stc=1&d=1507959986

 

 

It should be well over 50mm to not be a flow wall, this is the exact reason why I like the Invidia Uppipe.

2016 Edit: I recently discovered that OEM gaskets are much bigger then the ID of the uppipe, this is why the black ring is there, it's not from stock up pipe being that much smaller then the head exit.

 

http://legacygt.com/forums/attachment.php?attachmentid=256727&stc=1&d=1507959986

Edited October 14, 2017 by covertrussian
Picture Reupload

Invidia vs OEM catted turbo end:

http://legacygt.com/forums/attachment.php?attachmentid=256730&stc=1&d=1507961159

 

Invidia has smooth transitions inside the pipe, it does also have not an ideal taper on header end.

http://legacygt.com/forums/attachment.php?attachmentid=256733&stc=1&d=1507961159

http://legacygt.com/forums/attachment.php?attachmentid=256734&stc=1&d=1507961159

 

Compare that to the OEM uppipe, it's like it was purposefully designed to suck and reduce power.

http://legacygt.com/forums/attachment.php?attachmentid=256735&stc=1&d=1507961159

 

Turbo end shows the cat and EGT, notice how poor the transitions are.

http://legacygt.com/forums/attachment.php?attachmentid=256736&stc=1&d=1507961159

 

Invidia uppie has a bung for the OEM EGT, but oem EGT is meant for checking the health of the cat only, it's too far away to give accurate EGT, plus it can break and kill your turbo and finally I'm hearing they burn up faster without the cat. You will need a hard to find M12x1.25 bolt, parts stores do sell drain plugs in that size for around $5. I was able to find a plain bolt at local hardware store and cut it to fit.

http://legacygt.com/forums/attachment.php?attachmentid=256731&stc=1&d=1507961159

http://legacygt.com/forums/attachment.php?attachmentid=256732&stc=1&d=1507961159

 

Gaskets, now is the time to replace those 10 year old gaskets...

http://legacygt.com/forums/attachment.php?attachmentid=256737&stc=1&d=1507961159

 

Getting the uppipe was not hard, but trying to hold it and bolt a bolt up did get tricky, not enough hand room.

http://legacygt.com/forums/attachment.php?attachmentid=256738&stc=1&d=1507961159

http://legacygt.com/forums/attachment.php?attachmentid=256740&stc=1&d=1507961159

 

I personally tightened the the turbo bolts before getting the header attached, if you keep them loose it might make it slightly easier to get the header installed.

http://legacygt.com/forums/attachment.php?attachmentid=256739&stc=1&d=1507961159

http://legacygt.com/forums/attachment.php?attachmentid=256745&stc=1&d=1507961159

 

Get new gaskets on the header, and bolt everything up.

http://legacygt.com/forums/attachment.php?attachmentid=256741&stc=1&d=1507961159

http://legacygt.com/forums/attachment.php?attachmentid=256742&stc=1&d=1507961159

http://legacygt.com/forums/attachment.php?attachmentid=256743&stc=1&d=1507961159

http://legacygt.com/forums/attachment.php?attachmentid=256744&stc=1&d=1507961159

 

Now I didn't realize this until I started looking for exhaust leaks do to a whiny O2 sensor code. Apparently I put the second gasket ontop of the stock one, fitment is perfect and I see no leaks, thus I think this up pipe might actually be a little short, if it prevents cracks I'm all up for it too!

http://legacygt.com/forums/attachment.php?attachmentid=256748&stc=1&d=1507961159

 

All of this took about 4 hours, rusty parts and stuck bolts is the main reason for why it took so long. I'll do some Virtual Dyno runs in the next few days and will see how it did powerwise, also will see if MPG improves.

 

 

Results

Finally did a virtual dyno, I rest the ECU for both runs, and drove the car until IAM hit 1.0 that way timing would be identical for both runs. Waited for another warm day in November and did another run, compensating for temperature, pressure and fuel/toolbox weight. 7whp/10wtq peak gains!

http://legacygt.com/forums/attachment.php?attachmentid=256749&stc=1&d=1507961159

 

Do notice the AFR dip, this is a stock sensor thus it only reads to 11.1 and even then it's not accurate. I'll have my MTX-L hooked up after I get rid of the P11. Also please note that this is not necessarily the best road for peak WHP (slight up hill), but it's very easy for me to do repeat runs on this specific road. On a straighter road the car is making 213whp.

 

CEL Fixing

Removing the EGT sensor will cause a CEL, thus you have to either reflash the ecu with codes off (best method), or use a resistor patch (will work, but I've had some issues after some time).

 

Disabling the CEL's through reflash

Disabled these codes in your tune:

P0420 - Catalyst System Efficiency Below Threshold

P0545 - Exhaust Gas Temperature Sensor Circuit Low

P0546 - Exhaust Gas Temperature Sensor Circuit High

P1301 - Misfire Detected (High Temperature Exhaust Gas)

P1312 - Exhaust Gas Temperature Sensor Malfunction

P1544 - Exhaust Gas Temperature Too High

 

Resistor

I highly suggest using the reflash route, resistor patch for me would throw intermittent CEL's and cause cruise control to fail. Since I have re flashed the ECU with resistor disabling CEL's, I've never had this issue happen to me.

 

Get a 2.2-kohm 1/2-watt Resistor (Radioshack # 2711121), this resistor makes the ECU think the EGT is always at 1292 *F.

http://legacygt.com/forums/attachment.php?attachmentid=256746&stc=1&d=1507961159

 

Tape it off so it doesn't fall out

http://legacygt.com/forums/attachment.php?attachmentid=256747&stc=1&d=1507961159

Edited October 14, 2017 by covertrussian

excellent write up!

i have a catless sti uppipe sitting around waiting to install it, just debating what i should do tune wise, alot of mixed opinions on whether a tune is necessary or not.

what is necessary for the virtual dyno? and what kind of tune are you running, still stock?

Tune is not a must, but I would at least get rid of the Closed to Open Loop delay so that it's not as lean going into boost.

Valve cover gasket, leak much!

Dreading the day of having to replace them might wait till I have to pull the block anyway, or the turbo...

I don't blame you, I had a shop do my plugs and valve cover gaskets last fall. Although, many claim it's not difficult.

 

It's worth mentioning, bc when replacing/removing the OEM UP those bulky heat shields can ding the half moon gasket or valve cover gaskets, and cause the valve covers to leak even more than they are already prone to do.

 

Be gentle when removing and replacing the UP, don't just yank and pull.

Edited May 6, 2014 by BoozeRS05

Thanks so much for the write up! I am in the process of replacing my UP and DP (and other things) with Invidia catless replacements. So your write up came at an awesome time haha.

Just found this, yet another great post by covertrussian.

 

Looks like you didn't use PB Blaster or anti-seize compound.

Looks like you didn't use PB Blaster or anti-seize compound.

 

My Russian bear arms have enough torque in them not to need to.

Great write up! Thanks

So covertrussian, you did not have to loosen the engine mounts to pull the oem up pipe from the engine bay?

So covertrussian, you did not have to loosen the engine mounts to pull the oem up pipe from the engine bay?

 

On the Legacy didn't have to, the painful part was EGT sensor that was stuck. But on the Forester XT definitely had lift the engine up.

mmmmh. I have an outback XT. I hope I don't have to..

You should be fine, my motor mount bolts are starting to strip (probably from previous owner). Thus I hope to never have to loosen mine!

I wonder why you had to on the FXT though.

Much smaller engine bay (narrower). It's a ton easier for me to do spark plugs on the Legacy then on the Forester.

Interesting. I did not know that.

On the Legacy I can do spark plugs with just removing the stock airbox. On Forester XT I have to remove the battery and intake.

On the Legacy I can do spark plugs with just removing the stock airbox. On Forester XT I have to remove the battery and intake.

 

I don't know how you managed to replace the plugs like that, you must be a ninja! I removed my intake and battery, then jacked the engine up so I could get socket and extension on each plug without hitting the frame rails. Once I committed to lifting the engine though, it was a relatively easy 30min job.

 

Jim

You'd have to use a short extension. It usually works. I just did it on Monday. But yeah, it is a pain for sure..

It's no where near as easy as my inline 4 Nissan, but still not that hard, heck VQ35DE Altima's and Maxima's require you to remove the intake manifold to get to last 3 spark plugs.

 

I was able to do a compression test on all 4 cylinders on the legacy, it wasn't easy or fun (hot engine is hot), but doable.

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/Engine/Sparkplugs/LGTSparkplug_006.jpg~original

^ take off the intake manifold? Are you kidding me?? What the..

^ take off the intake manifold? Are you kidding me?? What the..

 

It's nuts, check it out here. I was debating between buying a Legacy GT or an Altima SE-R, and surprisingly Legacy GT is actually easier to work on in the engine bay

Horrible. Just horrible.