Spacer won't do much on a HR, it won't fit for starters   
  
The likes of Jez and Abbey can probably tell you about expected gains but sounds about right.. Don't get hung up on figures though, do all that and it will be like a different car, better throttle response, torque, power and sound   
  
Stillen Sway bars or Eibach are both really good  
  
http://www.tarmacsportz.co.uk/350z-stil ... -bars.aspx