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Hey all, thinking of the first few mods I'm doing to my 2017 WRX STI. When I bought the car the original owner had put on a COBB Intake and a COBB BOV. I was recently looking at Tomei ELH 4-2-1 and a Tomei single exit catback. I was wondering if I installed ELH and a catback would I need a tune to support them along with the intake and BOV?
Thank you!
 

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So it currently doesn't have a tune for the Cobb Intake? I'd address that first, or not drive it until you get the ELH installed then get it tuned. On the stock MAF you can't 'tune' for the BPV if it's not set on full recirculate. I'd either do that or just replace it with OEM which works just fine.

Technically ELH don't require a tune but you won't get the full potential without one, so essentially defeating the purpose of putting them on.

Catbacks don't require a tune.
 

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Lose the BOV, absolutely get a tune for the intake (not safe without one) and get a downpipe when you get the ELH, and get the car pro tuned. Downpipe and ELH are your power adders, usually ppl do the downpipe first but ELH are the cherry on top so get both.
 

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is it a BOV (blowoff), or a BPV (Bypass). I ask because if it's a BOV, venting to atomsphere, ditch it. however, cobb does make a BPV (bypass), which is essentially the same thing, just recirculated into the turbo inlet. if it's a bypass and already there, may as well just leave it. although it's not necessary esp on a stock or fairly small turbo. the oem bpv holds boost pretty well.

for your question of the tune. if it is not already tuned for the intake, stop driving it, and get a compression test done. make sure your motor isnt hurt. so far as the parts you mentioned, you WILL need to tune for the header, a catback you will not need a tune for (if you get them at the same time just tune for everything)

a catback exhaust is the ONLY mod you can do to the engine that will not require a tune. ANYTHING else, tune for it (often, tuners who did the initial tune, will charge a smaller fee for a tune adjustment for new parts, assuming you are simply adding a bolt on, not a bigger turbo/fuel/built motor etc)
 

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Does your ELH have a bung that fits your O2 sensor? A few weeks and ~500 miles ago, I installed a killerb elh, up-pipe, and cobb downpipe on my hatch. The ELH is bunged for an EGT, so i had to delete the front O2 sensor and disable the monitors.. eg a tune. I also took the opportunity to zero out wastegate duty until have time to log and optimize for parts [ and winter ;) ].

at a minimum, I would stay out of boost and off the send foot until you can log.
 

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Does your ELH have a bung that fits your O2 sensor? A few weeks and ~500 miles ago, I installed a killerb elh, up-pipe, and cobb downpipe on my hatch. The ELH is bunged for an EGT, so i had to delete the front O2 sensor and disable the monitors.. eg a tune. I also took the opportunity to zero out wastegate duty until have time to log and optimize for parts [ and winter ;) ].

at a minimum, I would stay out of boost and off the send foot until you can log.
No bung for a front O2 on the killer b? You deleted yours??
 

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yes. deleted front O2 and installed EGT in manifold bung and wide band O2 into down pipe bung. This caused two CEL codes to be thrown that I had to disable in the ROM.
So you also made changes to run open loop all the time I assume? I wouldn't recommend that for the OP. I'm pretty sure the killer b ELH has a front O2 bung with the option of an EGT bung in cyl 4 or an option for an EGT bung in all 4 primaries. I run the tomei EL manifold and kept my front O2. I deleted my rear O2 along with the required DTC.
 

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So you also made changes to run open loop all the time I assume? I wouldn't recommend that for the OP. I'm pretty sure the killer b ELH has a front O2 bung with the option of an EGT bung in cyl 4 or an option for an EGT bung in all 4 primaries. I run the tomei EL manifold and kept my front O2. I deleted my rear O2 along with the required DTC.
after this post, i checked the bung again and the O2 sensor does indeed fit. I never bothered to try because it was marketed as an EGT bung. However, the O2 sensor threads. Because I have been having so much trouble with the PLX wideband working with ROMRaider, I would love to install the wideband in the front O2 dongle and read wideband values through the ecm.

however, the wideband plug doesnt fit the stock O2 sensor plug.. So options are to splice and extend the harness of the OEM sensor to reach the KB ELH bung, or find a schematic so I can splice the OEM plug onto the wide band harness.

I'll have some time this weekend to try this..
 
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