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You can adjust one ;)

No, in all seriousness, and I could be completely wrong, as I've never gotten too much into this (yet), but I believe the differences are:

Non-Adjustable: The spring in the wastegate is set at a certain 'spring constant'. This constant allows a certain pressure to 'open' the waste gate, and allow blow-by directly back into your exhuast. People seem to state that this INCREASES their turbo spool up time, as they feel the spring is set at too LOW a pressure to open, so instead of spooling the turbo, there is some unneeded blow-by thus larger spool times.

The adjustable, obviously, let you adjust your spring constant, so that your wastegate can require MORE pressure in order for it to open, thus producing shorter spool times. The problem with this is that if you set your spring rate TOO high , thus requiring more pressure, is that you may get little turbo surges, that run higher than 14.5psi, at which point the ECU in your car will cutoff the fuel for a bit to reduce pressures.

Is this correct people?

bascially, by seting your waste gate spring constant, you're slightly increasing your PSI to the turbo , decreasing spool times, but are running the risk of a turbo surge/spike, and hitting the fuel cut off pressure (which as I stated above, I believe is 14.5psi on stock ecu's)

hope that helps,
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