VIAS stands for Variable Intake Air System. It is made up of a power rod going through your intake manifold that holds a series of butterfly valves. A solenoid turns the rod at 5000 rpm to open the valves to allow the engine to breathe better. Nissan VIAS video link.
The VIAS system is 100% of the reason 5th gen maximas have higher horsepower than 4th gen. All the 4th gen guys lust after VIAS intakes and buy them when they can.
However, the VIAS has a design problem - an extremely weak connection in the internal linkage that is destined to fail in 100% of 5th generation Maximas. You lose about 30 horsepower at the top end as a result. I didn't know what I was missing until I got those ponies back!
The good news is that it is very easy to fix - about 20 minutes of wrenching plus waiting for the JB weld to set. $5 for 30 HP - good deal! I took mine apart and fixed no problem. Here's how:
This is the VIAS solenoid unit. It is on the drivers' side of the intake manifold. Even if the solenoid works properly when you hit 5000 RPM, your internal linkage is still either broken or soon will be. The solenoid mechanism is held on with four very soft yet quite stuck screws. One of the screws is blocked by the throttle body.
This is the screw blocked by the throttle body. Some people are able to rotate the throttle linkage to get at it, but I simply loosened throttle body. It is NOT necessary to remove throttle body completely, nor remove any of the hoses attached to it. 
Hidden screw again. Be sure to use #3 Phillips or big slotted screwdriver on these screws. They are very soft and heads strip easily. You can also use impact type screwdriver or proper bit in drill. If stripped, can still be removed with vise grips.
Cup should be attached here: but it is broken off due to crappy design. Some owners find their cup is still attached, but loose. The cup should NOT be able to rotate independently of shaft. See how dirty mine is? Clean the whole area shown with brake cleaner as well as inside and outside of cup.
Now it's so clean it shines. Put a little JB Weld or JB Kwik on bottom of cup where it mates with solenoid shaft, then a good coating on inside bottom of cup. Try to keep sides cleaner than I did! Pay attention to cup "handle" orientation. You decide. Make sure everything rotates freely when you push lever on solenoid. 
Pressing the spring in while JB is tacky prevents a clearance issue with end of rod. Otherwise your pool of JB Weld may make cup too shallow for spring and rod. Doing this, you don't need to cut spring. Also, if you want to play with removing power rod later, you don't need to disassemble solenoid end. Let JB get good and hard before re-assembly. With Kwik, I'd wait at least 2 hours; regular JB should be left overnight at least.
 Reassemble and feel the power!
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