Ridetech system:
Not sure what car you looked at with the Shockwaves, but the ride height is lowered around 2 inches from stock on the first gen.
Here's a pic of Velocity at speed to illustrate the ride height:
The Coil over package uses all the same parts with the exception of the springs (of course Shockwaves use air springs while the coil over use Hyperco steel springs).
If you are not going to track the car and are not worried about a REALLY big front tire you can keep the stock subframe if it's in good shape. If you want a big front tire you'll need our TruTurn kit or replace the entire sub with the Speed Tech kit.
Speed Tech system:
Should you choose the Speed Tech system (which is quite nice, by the way) you can upgrade to our Ridetech coil overs.
Basically you are looking at cost. The front and rear Ridetech kit (using the stock sub) is $3800 ($4450 with the TruTurn).
The Speed Tech Track Time package with front sub and rear torque arm is listed at $9893.
I'm sure Blake will jump in here and correct me if any of this is wrong.