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Greetings,
I recently purchased a '02 WRX that is equiped with an aftermarket Boost gauge with MPa indication. The car was purchased in the SF Bay area, very close to sea level. I reside at 4,750' elevation and I have noted that the boost gauge indicates a slight negative reading with engine OFF and key ON.

Based upon long ago flight training, I recall the need to reset altimeters due to barometric pressure differentials relative to base elevation. I assume this is why the gauge currently reads slightly negative. The negative reading is approximately.005 MPa or roughly .73 PSI. I have also noted that the maximum boost indicated in 3rd gear full throttle mid-powerband operation is .8 MPA, or, with correction about 12.32 PSI boost. Is this about correct for a stock set-up?

I don't seem to have any documentation with the gauge. In very small print on the bezel is the name laMco. I'm wondering if there is a recalibration adjustment that can easily be made or if I should merely calculate the error when dialing in my soon to arrive manual boost controller?

Lastly, from the numerous discussions I have read here, I assume elevating the boost to about 15PSI is fairly safe. Is that correct ? (assuming I calculate for the error in my boost gauge reading)

My overall plan for the car at this point is the MBC, a full exhaust system upgrade including the Gruppe-S manifold, up-pipe, Perrin hi-flow cat down-pipe, mated to the existing Supersprint cat-back, Samco hoses and an STi intake scoop. I'm shying away from pulleys at this point untill I sort out the initial upgrades to see if it is satisfactory. For serious acceleration fixes, I ride an Aprilia RST1000 :eek:
 

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Your boost gauge might be broken.

Vaccum pressure for the intake manifold should be -0.06 Mpa with the engine started . And ZERO wherever else you go when the engine is off...

A boost gauge measures relative pressures not absolute pressure. So altitude should have no effect on its proper functioning.

I had a broken gauge problem and I sent it back to subaru. Im guessing at WOT and full turbo spool you are getting readings blow what it is supposed to be. It is supposed to be at around 0.09 to 0.1 Mpa at full boost in 3rd gear.
 

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Your boost gauge sounds like it's a little off. I have the same LamCo gauge up here at 5300 ft and it reads dead on zero when the engine isn't running.
 
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Your boost gauge sounds like it's a little off. I have the same LamCo gauge up here at 5300 ft and it reads dead on zero when the engine isn't running.
Weird, I just got off the phone with Prosport cuz I just bought one of their gauges a few days ago and here in Colorado I'm reading 9 inHG (major vacuum) and not 0 here with key in ignition, engine off. Prosport told me it's NORMAL due to my altitude. Yet, my ECU is reading PSI of 14/15 and upwards....yet the gauge is only reading max levels of 11PSI
 
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