Nitrous Help
The window switch will give you a starting RPM amnd ending RPM for each stage. You can set the unit to activate one stage at regular activation and set the second RPM to activate at a certain Gear if you would like. This may come closest to what you are looking to do.
The NOS progressive will let you give it a starting percentage to a ending percentage with in X amount of time. This is called a time base ramp.
If you plan on going with a windowswitch I would suggest this one over the ZEX. It has the same features as the Zex exept for it has a built in TPS activation and cheaper.
http://www.nitrousoutlet.com/catalog...product_id=964

