here is the link http://infinitipa.zoovy.com/product/14010-AC805
long story short; can anybody explain to me what this does for your car?

 

On a pre 2005 VQ35 without variable valve timing on the exhaust side it lowers you horsepower by 7-10 from 3000 RPM to 6200 RPM. It also lowers your torque about 10 ft lbs. But it gives 5-7 more HP from 6200 to 6500 RPM. This is based on a before and after dyno posted on 350zmotoring.

 

so overall is this mod worth it?

 

I would say no it's not worth it. You will gain a few ponies up at 6k rpm, but lose down lower and more importantly you'll lose torque.
As the write-up says, for higher revving situations.
C.