What are the spring rates front and rear? Are the sway bars changed?
stock suspension will be numb and slow to react for those power levels on the street. It will also roll over on itself and pretty much suck.
Putting your customer in a higher quality shock/spring is your answer. JRZ, MOTON, PENSKE. Spring rates depend upon your customers exact use.
Doing a complete hands on/laser alignment and setting the compression/rebound/ride height/rake/corner weights for precision control on the street/track is also key.
Or:
You can take it to an alignment rack at the local tire shop with some bargain basement shocks with crud springs and you'll get the wagon wheel ride with no control
