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07 wrx turbo upgrade

1212 Views 3 Replies 4 Participants Last post by  EJ257
hey all, came across a great deal on a APS SR40 turbo and was wondering if it would be a worthwhile upgrade over my VF48 from a 2012 STi

I have a better bellmouth dp, tial 44mm ewg, grimmspeed uppipe, apexi catback I'm going to have installed so adding a turbo isn't an issue


07 wrx TR
EJ255 w/ 2012 sti vf48
STi TMIC & manifold
HKS catless downpipe
turboXS midpipe into STi axleback
grimmspeed pulley & ECBS
walbro 255

tuned by EFI logics in CT 298 whp/318wtq (open source)

I'm very happy with how the car drives but I can get a screaming deal on the APS SR40, so even if it's only marginally better I would still be interested. I need to get retuned as well anyway with the ewg.

I know I'll get some gains from the less restrictive exhaust and ewg and but I want to keep whp/wtq around 350 due to reliability and longevity being top priority. this is my daily

I should be able to run on the stock injectors right? I have some 850cc ones from a friend I can use as well...
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You're going to need bigger injectors to have any gains, you may need to upgrade your clutch, too.
Yeah. honestly the stock injectors are probably maxed out and holding you back now with your current setup. Pick up a set of ID1050x's and go from there.

I am not familiar with the sr40 turbo. So I don't want to say if it is or isn't an upgrade for the VF48. That would be another good question for your tuner who I am sure has knowledge about the turbo you are asking about.

Even if it turns out that you keep the vf48 on your car, I would still invest in the injectors mentioned above then get retuned.
SR40 is equivalent to like an OG 20G turbo on the Subarus (~44lbs/min).

You're already maxed out on your injectors, so even with the VF turbo, you'll want to upgrade them by the time you get retuned, even if it's just for the EWG / new catback. Add a bigger turbo, and you'll be downgrading if you don't upgrade the fuel system.

As for the downpipe, keep the HKS one; there is no benefit to upgrading when you hold the wastegate shut for EWG. Had I known how quickly I'd add an EWG to my setup, I'd have never flipped the HKS downpipe I had. Sell the downpipe and put that money towards injectors / EL manifold / TMIC. Those would be much better ways to invest in terms of power than a bellmouth downpipe that is going to do nothing.
1 - 4 of 4 Posts
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