Works kit gets you:
Ported Head
Intake upgrade
Cat-back upgrade
Reduced Supercharger Pulley (you used to get an upgraded S/C as well but it is standard now)
Bigger injectors
Re-Flashed ECU with JCW software
I was unaware that was running8K I paid 6K for mine installed.
You can do the aftermarket thing but be warned it is not a s smooth as the JCW kit. You will get more raw peak HP but you will not get as much mid-range as the JCW gets you.
That said go here and look around this is a comparable forum to Pelican.
http://www.northamericanmotoring.com/
I have used MYMini in Florida for my upgrades to my suspension and I strongly suggest giving Pete a call, he loves to talk to new owners and help them with decisions. His customer service is great.
http://www.myminiparts.com/