Hi lewis
If you're planning on racing the cat at coastal's off road track (bumpy grass) I'd recommend the Grant Williams Cat SX1 base set up (can be found on here in the cat set up thread), the main differences between that & the PB set up being drilled shock pistons, longer shock ball joints & weight on/under the chassis (among other things)...
Do these & will glide over the bumps & feel much 'safer'
There are other changes but doing just these low cost ones will make a real difference for starters.
May not be your cup of tea but made a real difference for me
Ben