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5th gen exhaust for stage 2


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I've read the power mods sticky and modeling my power upgrade around it. Stage 2 stock turbo with DP and TMIC upgrade and change out the BPV for reliability.

 

It's already noted there that stock exhaust is good to above stage 2. Also mentioned all over the net for Subarus in general. It wouldnt be cost-effective or really neccessary to do it at this stage.

 

That said a lot of users here are at that level with exhausts anyway just because we can. :)

 

I have a few options I am considering after the DP:

 

Keep current set up: mating the 3" D/P with the stock midpipe with a Grimspeed adapter, and keeping my custom 2-1/2" Borla axlebacks.

 

Stock midpipe with custom 2-1/2" Y-section and 2-1/2" branches all the way to the Borla axlebacks. To get rid of the crappy tiny stock Y.

 

Custom midpipe with new resonator 2-1/2" to 3" (stock looks to be 2-1/4") to the 2-1/2" axlebacks.

 

Interested in everyone's thoughts.

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Well, the stock mid and the crappy tiny stock Y-pipe may or may not end up being the only thing that can keep boost in check, so that'd definitely be a good reason to consider keeping those parts. Definitely port the wastegate if you do plan on opening things up downstream of the downpipe, and it'd probably be a good idea even if you do end up staying with the stock mid/Y.
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Nope, my exhaust flow is still restricted by the cardboard box my downpipe is in :p

 

I'm still deciding how far down the rabbit hole I actually want to go, but I do plan on porting the wastegate somewhere along the way.

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I have swapped out my downpipe with the nameless part and left the stock catback and have had no boost creep issues. My boost is very well controlled in the tune, I have room to tune out any creep if the need arose. I would be interested to see if your mufflers make any difference.
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I have swapped out my downpipe with the nameless part and left the stock catback and have had no boost creep issues. My boost is very well controlled in the tune, I have room to tune out any creep if the need arose. I would be interested to see if your mufflers make any difference.

 

I wonder if your humidity and warm temps help to keep your boost in check?

I really did notice a jump in boost with 40F and dry air this fall. I have hot and humid in the summer here as well and a drop in boost.

 

So, maybe Scubaboo would be fine with the warm and humid temps of the Philippines and opening the exhaust...?

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Nope, my exhaust flow is still restricted by the cardboard box my downpipe is in :p

 

I'm still deciding how far down the rabbit hole I actually want to go, but I do plan on porting the wastegate somewhere along the way.

 

Lol me too! Hence this thread.

 

 

 

 

I have swapped out my downpipe with the nameless part and left the stock catback and have had no boost creep issues. My boost is very well controlled in the tune, I have room to tune out any creep if the need arose. I would be interested to see if your mufflers make any difference.

 

 

I wonder if your humidity and warm temps help to keep your boost in check?

I really did notice a jump in boost with 40F and dry air this fall. I have hot and humid in the summer here as well and a drop in boost.

 

So, maybe Scubaboo would be fine with the warm and humid temps of the Philippines and opening the exhaust...?

 

I have read its a cold weather thing. I just got my boost gauge on a few months ago and havent really checked for creep, but I dont feel anything untoward with my 2-1/2" axlebacks. They are very far downstream after the stock Y though.

 

What boost range are you guys seeing btw as normal?

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I noticed a difference when I switched from the stock cans to the Nameless 5", but nothing outside the range of what the OTS tune was able to handle. I believe FLlegacy was in about the same boat when he was running the Nameless 5" cans, which would make sense, considering I bought my mufflers from him.

 

I think I'm usually closer to 14 psi during the summer, and right at the 15 psi target in the winter. Up until the ECU goes into buzzkill mode at about 15-20 degrees and starts trying to keep the transmission intact, at least.

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Just looked back at some Torque App screenshots i have.

 

Pre-axleback: peak boost right at 14psi, air temp 37c.

 

Post axleback: peak boost a bit above 14psi, air temp 30c.

 

Not enough of a sample to conclude anything really but I dont think the axlebacks are a factor at this point.

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Just looked back at some Torque App screenshots i have.

 

Pre-axleback: peak boost right at 14psi, air temp 37c.

 

Post axleback: peak boost a bit above 14psi, air temp 30c.

 

Not enough of a sample to conclude anything really but I dont think the axlebacks are a factor at this point.

 

biggest downside of the stock axle back is the weight, those sucker are heavy!

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biggest downside of the stock axle back is the weight, those sucker are heavy!

 

This is a very good point. When I installed my Nameless axlebacks, I did a stand test on my bathroom scale of me and then me+nameless, and then after install, me+stock axleback, and the stock axlebacks weighed 14 lbs a piece while the Nameless weighed only 7 lbs each, for a total of 14 pounds of weight saving from install. Weight dropped is weight dropped.

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This is a very good point. When I installed my Nameless axlebacks, I did a stand test on my bathroom scale of me and then me+nameless, and then after install, me+stock axleback, and the stock axlebacks weighed 14 lbs a piece while the Nameless weighed only 7 lbs each, for a total of 14 pounds of weight saving from install. Weight dropped is weight dropped.

 

are you saying the stock cans only weighed 14 lbs a piece? i would have pegged them closer to 30 lbs?

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I see 20.9 psi pretty regularly 21.0x when its chilly out. My WGDC is around 67% IIRC and boost error is pretty low. It has been a while since I logged a run I might do that this week just to see if anything stands out.

 

The high here today was 12deg F. Whats "chilly" in your hood? 65f? **** thats short weather for me :lol:

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