Hey guys. Been lurking here a bit while thinking about what color G to get and reading all the posts, but this is my first. Think I've landed on the IP as a color. Was wondering if anyone has tried an underdrive pully on the 2007 yet and what gains resulted therefrom?

 

If I am not mistaken, I beleive UD pulleys are beneficial in FI applications (e.g. supercharged) where one would like to spin it up faster.

 

UD pulley's are not good for FI, you're thinking of the pulley on the supercharger itself that people like to get a smaller one for more boost. I dont think any companies have made an UD pulley for the VQ35HR yet.
-GP-

 

Oh ... are you saying larger pully on a component to spin it slower?

 

yeah, that will increase the travel
-GP-

 

Most underdrives are lighter in weight, to reduce rotational inertia (help the engine spin quicker) and smaller, to reduce paracitic draw of the belt driven accessories (P/S, A/C, etc) They can cause electrical output to be low at idle.

 

that being said, I haven't seen one out yet. Sometimes they are fluid-filled harmonic balancers, and shouldn't be removed.

 

UD are also smaller in diameter too. With that many electronics and HID lights, I'm not sure if you really want UD pulleys. In turbo applications, I've seen some dynos with only 2-3 hp gain. You 'll probably get better gains using that money to get lighter weight wheels to fix inertia problems.