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Discussion Starter · #1 ·
Morning gents! (morning here in AK still)

I'll be getting a lot of crap for this, that's natural. But I'm very interested in upgrading my exhaust from the turbo-back. I currently got my hands on an up-pipe, my research shows it's best to also purchase a 38mm Tial Wastegate with a v-band clamp to go with that. I've been told to possibly invest in a dump-tube? Any insight on that would be great, from what I know... the up-pipe is the best initial mod for the WRX.

My choice for exhaust is the Cobb Tuning SS 3" cat-back, and i'll be adding an Invidia cat-less downpipe. My question regarding the downpipe... is what is the difference/benefit of the divorced wastegate type? Which version is best for my setup?

Again, up-pipe/down-pipe/cat-back exhaust... with all of that - what all would I need to support this and tune it? Go easy on me, I'm not 18, I'm 32 - and this is my first turbo car other than a 99 VW Passat 1.8t (which was rightfully bone-stock, as it should be). So I'm not looking to take this off jumps, just have a modest upgrade in power and some good tone as well.

Any help or suggestions are welcome. Not trying to gain enemies or haters, just want the best results for my car. I appreciate it. Thanks guys!
 

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No one's gonna hate on your for a TBE, now if it were a non-recirc blow off valve, then yes you would be roasted accordingly. Now for your car, an downpipe will require a tune for it to get peak horsepower out of the modifications and to run safely. Many people use a cobb accessport with their set up as it's a great and relatively simply tuning software. In regards to Tial Wastegate, if seems relatively unnecessary for me unless you are going for bigger power numbers in conjunction with other mods. A TBE and a tune sounds like a great starting point to me.
 

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I currently got my hands on an up-pipe, my research shows it's best to also purchase a 38mm Tial Wastegate with a v-band clamp to go with that.
Meh.

Again, up-pipe/down-pipe/cat-back exhaust... with all of that - what all would I need to support this and tune it?
If you'd not mentioned the fancy waste gate, my answer would be "nothing." You can run an up pipe, down pipe combo on your car without any tuning. It'd generate two different CELs, each of which you could deal with (one with a resistor and the other I suppose with an anti-fouling adapter for a spark plug like they used to sell in the 1970s).

I don't know about the wastegate though -- I suspect that'd complicate things and would require you to remap the car. I don't remember at this point, sorry.
 

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Your car is nearly 15 years old, and if it's spent it's life in snowy areas, make sure you have a good full inspection of the vehicle. Is all maintenance up-to-date? When were all the mounts / bushings replaced? There may be some wear/tear items that should be addressed before worrying about adding power.

That said...



EWG on your car would yield negligible benefits, unless you just really like the sound of a VTA wastegate dump (it's quite loud / obnoxious when it opens up, which is fun when you find yourself going through a tunnel). The extra costs associated with this modification would be far better off invested elsewhere. As long as the uppipe is catless, don't waste your time with an external wastegate setup.

The catback in question tapers down to a 2.5" donut gasket, where the downpipe mentioned is a 3" flat flange; you will either need to buy an adapter, cut the taper off and weld in a 3" section and flange, or deal with an exhaust leak. While this exhaust leak won't really impact performance, it can be annoying to listen to "tick tick tick" as you drive by every guard rail.

In theory, a divided / divorced wastegate design is ideal, as it allows the exhaust gases to be expelled without interference from each other in the upper housing. That said, your turbo is small enough that it wouldn't really show any real-world benefit, and by the time you get a turbo large enough to show real-world results, you're better off going external, anyway. Personally, I'd always take a bellmouth design, and upgrade to EWG down the road, if needed.

Living in AK, what is your "premium" pump gas fuel? 90 octane? Base maps like the ones included with a Cobb AP purchase are designed for 91/93. You might be able to get away with their standard 91 or 91ACN map (AZ/CA/NV gas is worse than most 91-octane found in the states, so it's detuned even more), but you might not, and would have to look into custom calibration (either in-person or via email). If you have a laptop, you can look into a Tactrix cable and free ECU software (ECUFlash / Romraider) which could allow you to get an email tune from someone (basically, they send you a map, you datalog it, return the logs, and they adjust until everything is in line). Considering it's an '03, you aren't FORCED to calibrate the ECU, but not doing so would be like someone buying $200 running shoes to walk a block to/from the corner store every day.

You should probably look into gauges. Having both a boost gauge and WBO2 gauge would be useful when it comes to the tuning aspect (especially if you're going to have to get a custom calibration). If you want a digital boost gauge, go with AEM; if you want an analog boost gauge, go with Defi. For WBO2, the two big names are Innovate and AEM; AEM is cheaper and doesn't have the calibration issues that some people complain about with the Innovate, so I would go with them. SMY sells a pod that goes around your dash cluster which would be perfect for these two gauges, and is relatively subtle (compared to either pillar / clock pod).
 

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Discussion Starter · #5 ·
No one's gonna hate on your for a TBE, now if it were a non-recirc blow off valve, then yes you would be roasted accordingly. Now for your car, an downpipe will require a tune for it to get peak horsepower out of the modifications and to run safely. Many people use a cobb accessport with their set up as it's a great and relatively simply tuning software. In regards to Tial Wastegate, if seems relatively unnecessary for me unless you are going for bigger power numbers in conjunction with other mods. A TBE and a tune sounds like a great starting point to me.
Thanks dude lol, i'll definitely be straying far from a BOV. I appreciate the info man, I'm not sure about the wastegate anymore. Doesn't seem necessary (yet).
 

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Discussion Starter · #6 ·
Meh.



If you'd not mentioned the fancy waste gate, my answer would be "nothing." You can run an up pipe, down pipe combo on your car without any tuning. It'd generate two different CELs, each of which you could deal with (one with a resistor and the other I suppose with an anti-fouling adapter for a spark plug like they used to sell in the 1970s).

I don't know about the waste gate though -- I suspect that'd complicate things and would require you to remap the car. I don't remember at this point, sorry.
You are completely correct, the waste gate may throw me for a loop. I'm not trying to make this a screamer, so that's not at all my intentions. I was more curious on if it's a better investment than NOT having it, like will it affect me in the long run? I don't see myself adding anymore parts to this for a while. The TBE and perhaps an intake will be the only upgrades I will have. The waste gate at this point seems unnecessary. I really appreciate your insight man, that's the info I'm looking for.
 

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If you do not add anything beyond an exhaust and an intake, then I see no reason for an external wastegate.

(I disagree with using "intake" and "upgrade" in the same sentence, incidentally. I see no reason to waste your money).

Have a close look at EJ257's post above, I'd follow his advice.
 

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Discussion Starter · #8 ·
Your car is nearly 15 years old, and if it's spent it's life in snowy areas, make sure you have a good full inspection of the vehicle. Is all maintenance up-to-date? When were all the mounts / bushings replaced? There may be some wear/tear items that should be addressed before worrying about adding power.

That said...



EWG on your car would yield negligible benefits, unless you just really like the sound of a VTA wastegate dump (it's quite loud / obnoxious when it opens up, which is fun when you find yourself going through a tunnel). The extra costs associated with this modification would be far better off invested elsewhere. As long as the uppipe is catless, don't waste your time with an external wastegate setup.

The catback in question tapers down to a 2.5" donut gasket, where the downpipe mentioned is a 3" flat flange; you will either need to buy an adapter, cut the taper off and weld in a 3" section and flange, or deal with an exhaust leak. While this exhaust leak won't really impact performance, it can be annoying to listen to "tick tick tick" as you drive by every guard rail.

In theory, a divided / divorced wastegate design is ideal, as it allows the exhaust gases to be expelled without interference from each other in the upper housing. That said, your turbo is small enough that it wouldn't really show any real-world benefit, and by the time you get a turbo large enough to show real-world results, you're better off going external, anyway. Personally, I'd always take a bellmouth design, and upgrade to EWG down the road, if needed.

Living in AK, what is your "premium" pump gas fuel? 90 octane? Base maps like the ones included with a Cobb AP purchase are designed for 91/93. You might be able to get away with their standard 91 or 91ACN map (AZ/CA/NV gas is worse than most 91-octane found in the states, so it's detuned even more), but you might not, and would have to look into custom calibration (either in-person or via email). If you have a laptop, you can look into a Tactrix cable and free ECU software (ECUFlash / Romraider) which could allow you to get an email tune from someone (basically, they send you a map, you datalog it, return the logs, and they adjust until everything is in line). Considering it's an '03, you aren't FORCED to calibrate the ECU, but not doing so would be like someone buying $200 running shoes to walk a block to/from the corner store every day.

You should probably look into gauges. Having both a boost gauge and WBO2 gauge would be useful when it comes to the tuning aspect (especially if you're going to have to get a custom calibration). If you want a digital boost gauge, go with AEM; if you want an analog boost gauge, go with Defi. For WBO2, the two big names are Innovate and AEM; AEM is cheaper and doesn't have the calibration issues that some people complain about with the Innovate, so I would go with them. SMY sells a pod that goes around your dash cluster which would be perfect for these two gauges, and is relatively subtle (compared to either pillar / clock pod).
First off... just wanna say thanks. I read your write-up about this topic and it's been extremely helpful, as well as the info you've listed above. So yeah, much appreciated dude.

The car was originally bought in Vermont, lived half it's life there and half it's life here in Juneau. It's been religiously maintained at a Subaru dealer it's entire life, the owner was a Civil Engineer who had no problem keeping up with maintenance and replacing parts when need be. The undercarriage is amazing for how old it is, bushings and suspension overall are in great shape. As for the mounts, that's something I'm going to replace them asap, I've read threads on here about people preaching the good word of replacing before bumping up the power.

My up-pipe is indeed catless. Thanks for clearing that up, I've gotten mixed responses in regards to the up pipe and it seems like it's straight forward to go catless.

The cat-back donut gasket and flange... is there a preferred place to buy these? I figure i'll just get them on FastWRX when I get the exhaust/downpipe. There is the 3" donut gasket and a 3" 2-hole reinforced gasket..? Sorry for the newb questions, I'm just trying to piece it together.

As for the downpipe, it's sounding like a divorced is the best choice? As in with a catless up pipe and cat-back, it should be plug and play (with a tune)? Is your choice Bellmouth because of your setup, or is that what you would prefer for a setup like mine? Again, the newb questions will get easier for you in time lol. Your knowledge is extremely helpful!

For the record, the running shoes metaphor is amazing lol. You're absolutely correct, our premium gas here is weak. 90-91, honestly not sure if anyone has 92 anymore. Juneau only has so many options, so it's lame. There is a local shop here who specializes in WRX/STi's, they have all the cables/laptop software i'll need for a tune.

My car came with the Boost gauge on the steering column. I'll be purchasing the EGT & A/F gauge at the same time as the TBE system. Digital A/F for sure! That cluster looks rad, but I'm wondering if it'd look too wonky with the boost gauge on the steering column? I'm beyond stoked to finally be investing in a vehicle I love and will be keeping forever. Your help is seriously appreciated EJ257!!!
 

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Discussion Starter · #9 ·
If you do not add anything beyond an exhaust and an intake, then I see no reason for an external wastegate.

(I disagree with using "intake" and "upgrade" in the same sentence, incidentally. I see no reason to waste your money).

Have a close look at EJ257's post above, I'd follow his advice.
Indeed, I'm the same - but it's an upgrade cosmetically in the engine bay! How about that! Lol. Thanks again, any and all help/suggestions are welcome.

EWG is definitely out of the picture now. Saves me time and money.
 

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Ok so if you do chose a different intake I'd make sure you map the car for it.
 
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