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Discussion Starter #1
I have the GM Tune that gives my GXP 290hp. I as wondering on average what the turbo PSI should be? I am getting between 17-20 psi. I am just wondering if this is normal?

p.s. i did back off the waste gate because before the tune, i had done the waste gate mod. After the tune, i didn't want to hurt the turbo so i backed it off. I don't know if I am factory setting. I just know i backed it off a bit. Car seems to be moving really quick though.
 

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Sounds about right. Part of the added HP confusion surrounds the computer having the ability to self-turn or learn-down traditional performance enhancements. For example; you'd think that if you also added a Solo high-flow cat back system you'd pick up a modest increase of about 10HP to take it to around 300HP. But if the HP is directly related to the ability of the computer to self-tune than theoretically it's self-tuning itself back to 290.
 

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Here in KC when I had GM tune it was a fairly steady 21psi. Where are you located Midas, or how many feet above sea level. Also, it takes several key cycles to improve performance after the GM tune is first loaded.
 

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Discussion Starter #6
I am in San Antonio and we are 650 above sea level. I remember getting 21 psi when I initially got the tune. The issue I think was that I did the wastegate mod before the GM tune. Then when I decided to get it, I attempted to return the wastegat back to factory setting. Something tells me I didn't get it just right and that's why my turbo is shutting down. I did back it off a couple of turns more and now it seems to be very responsive and quick.

I hope this forum never goes away. I've learned so much from you guys. Thanks!!;)
 

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Cool - Yep - we are at 800 sea level so should be similar. Glad you got it dialed back.
 

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Sounds about right. Part of the added HP confusion surrounds the computer having the ability to self-turn or learn-down traditional performance enhancements. For example; you'd think that if you also added a Solo high-flow cat back system you'd pick up a modest increase of about 10HP to take it to around 300HP. But if the HP is directly related to the ability of the computer to self-tune than theoretically it's self-tuning itself back to 290.
With the GMPP or other tunes, isn't the learn down "turned off" (or at least off within certain parameters), i.e. adding a solo cat and 15hp is going to add 15hp since the tune will allow this within it's parameters?
 

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With the GMPP or other tunes, isn't the learn down "turned off" (or at least off within certain parameters), i.e. adding a solo cat and 15hp is going to add 15hp since the tune will allow this within it's parameters?

I hope so, I'd feel more comfortable displaying/claiming 300HP . I went a Solo cat back system (no free flow Solo CC) due to the coupes inherent cabin drone concerns.
 

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What were you getting before the tune? I bought my gxp as a salvage title, so there aren't exactly sterling maintenence records, but my boost hits 20, and I haven't done anything to it. I've been wondering if the previous owner did anything, but don't know how to find out. I'm also in San Antonio.
 

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What were you getting before the tune? I bought my gxp as a salvage title, so there aren't exactly sterling maintenence records, but my boost hits 20, and I haven't done anything to it. I've been wondering if the previous owner did anything, but don't know how to find out. I'm also in San Antonio.
Sounds high for an untuned engine. 16 or so it more typical. Look for the GMPP sensors, and failing that you'd have to have the car scanned to see what the programming is - but be aware that non-factory tunes can affect warranty, so having the dealer do the scan might not be a good plan.
 

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Sounds high for an untuned engine. 16 or so it more typical. Look for the GMPP sensors, and failing that you'd have to have the car scanned to see what the programming is - but be aware that non-factory tunes can affect warranty, so having the dealer do the scan might not be a good plan.
Being a salvage title, warranty is sadly not a concern for me, and I don't have the gmpp sensors. I should add that the 20 psi is a peak number, not constant.
 

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I'd go get it scanned, or ask someone on this forum that lives near you and has HP on their laptop (I believe they may be able to see what has been reflashed - correct me if I am wrong) to look at it. I don't recall having heard of a stock engine doing 20 psi.

Lots of tunes out there that use the stock sensors.
 
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