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12 Golf R w/ stock downpipe...does this limit boost capability?

91a2jettavr6

New member
I'll be adding both an APR downpipe and intake in a week or so. In the meantime, my question is this: will having a stock downpipe prevent boost from building beyond a certain level? If so, what would that level be (roughly)? I set my stage 2 loaded tune to 28 (I do have a HPFP installed) as I am experimenting and my boost gauge, which does work properly, shows 24-25 max at WOT and 20 vacuum at idle, just as it should. Anyway, is the restrictive nature of the stock downpipe preventing boost from building beyond this point? Can I expect an automatic increase once I've installed the aforementioned APR goodies? Thanks guys :) .
 

radplaid

New member
What I was explained at the performance shop here that did my car was, once the downpipe is installed you can expect your power band to start at a lower rpm and an increase in torque. 15-20 hp gain to be expected, but not necessarily pushing any more boost than what you are currently reporting.




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91a2jettavr6

New member
What I was explained at the performance shop here that did my car was, once the downpipe is installed you can expect your power band to start at a lower rpm and an increase in torque. 15-20 hp gain to be expected, but not necessarily pushing any more boost than what you are currently reporting.




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Ok, thanks for the response. So...if my boost gauge (South Performance) appears to be working normally and the car runs well and pulls HARD, what else would explain the 3-4lb deviation from the 28lb set point of my tune?
 

keihin

New member
You've got both stock intake and outlet restrictions, and likely a fuel restriction as well. It sounds like your software may be pulling you back from a potential overboost/lean condition.
 

91a2jettavr6

New member
You've got both stock intake and outlet restrictions, and likely a fuel restriction as well. It sounds like your software may be pulling you back from a potential overboost/lean condition.

Why would I have a fuel restriction with an APR HPFP given that it is all that is required (from a fueling standpoint) to run my stage 2 tune?
 

vizzlebizzle

Passed Driver's Ed
stage 1+ requires JUST the HPFP upgrade. you shouldn't have stage 2+ software until you have the downpipe/exhaust/whatever you're doing. and it's a gain of 25whp and 43tq, according to the APR website (going from 1+ to 2+)
 

thegave

Ready to race!
What I was explained at the performance shop here that did my car was, once the downpipe is installed you can expect your power band to start at a lower rpm and an increase in torque. 15-20 hp gain to be expected, but not necessarily pushing any more boost than what you are currently reporting.




Sent from my iPhone using Tapatalk

Boost pressure is simply a measure of restriction. Higher boost doesn't necessarily mean higher power.
 

91a2jettavr6

New member
stage 1+ requires JUST the HPFP upgrade. you shouldn't have stage 2+ software until you have the downpipe/exhaust/whatever you're doing. and it's a gain of 25whp and 43tq, according to the APR website (going from 1+ to 2+)

Actually, stage 2 (** United Motorsports) is comprised of their stage 2 tune and an HPFP...nothing else. Stage 1 didn't require the pump upgrade...only the stage 1 tune. There was no stage 1+ option. Stage 2+ (from what I understand) will be after I've installed the APR downpipe.
 

vizzlebizzle

Passed Driver's Ed
oh true. yeah, i don't know anything about UM tunes. i hear they're nice though. saw you using APR parts and thought you had the tune, too. my b. i didn't know UM had any tunes beyond stage 2 (other than bt stage 3)
 

91a2jettavr6

New member
oh true. yeah, i don't know anything about UM tunes. i hear they're nice though. saw you using APR parts and thought you had the tune, too. my b. i didn't know UM had any tunes beyond stage 2 (other than bt stage 3)

They really don't but I've decided to tell myself I'll have a stage 2+. Ahhh...I love denial.
 
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