I just got my Defi D boost gauge from lancershop.com last week. I had the calibration lab here at work run a pressure check to see how close it was to actual. He hooked up a bunch of crap to it and it turned out to be pretty accurate. With the multipule pressure and vaccum points that he ran, I'd have to say the gauge is within ± 0.25 psi.

I put it in my car Friday night, and low and behold I'm peaking at (if not over) 21 psi and it holds between 19 and 20.

I thought 20 psi was the peak for the stock turbo. Is there any possibility that mine came out of the factory set over 20? Has anyone else seen this?

 

the 05's run 20.8 psi from stock because of the 10.5 hotside on the turbo, its fine. The efficeny on the turbo kinda depends on the gas you run. I run 101 and push about 23 and leans to 21 by redline.

 

That's what I see, a spike to 21, then holds at 20.

 

Awesome. Must be nice to have access to labs like that .

Man... all these +'s to the 05 models. Makes me feel like I got jipped for buying an 04. Well until I step on the gas, then it's all good.

 

really??? 20.8 lbs of boost? stock?? im shocked. everyone always asks me how much im running i was always under the impression it was 19.0 lbs stock

 

I thought it was 20.3 lbs. spike, then tapering off. Mods could affect things though...

 

Yep! 05 are 20.3 psi stock! and 03-04 are supposed to be 19.5 or 19.7, something like that!

 

It shouldn't matter whether it's an 04 or 05. You end up modding the car anyway. So things even out.

 

There are two things wrong with this statement. First the hotside, a bigger hotside will actually make it "easier" for the stock setup to run lower bost, not higher. It's a step in the wrong direction. As you increase the area like the 10.5 hotside does, the wastegate will have to bypass "less" exhaust to maintain stock boost. Also, the backpressure on the cylinders will be reduced due to easier exhaust flow, which allows even more charge air into the combustion chamber, further lowering boost potential. Yes it makes more power, but it makes more power at lower boost.

Secondly, The efficiency of a turbo has nothing to do with octane rating. If you run higher octane gas, and don't take advantage of the ability to increase timing, you will actually lose hp and exhaust energy which spins the turbo. Higher octane gas "burns" slower. Putting in higher octane gas with the same timing will be a bad thing, not a good thing. Unless you have some sort of ignition control or the stock timing maps are programmed well enough to account for 101 octane (highly doubtful), running that juice is going to slow you down, and slow down your turbo efficiency.

 

My 05 spikes between 21 and 22 psi. Tapers down to 18 or so. All stock.

 

the specs say 20.5 @ 3500RPMs, tapering off to 16.5 by redline