I was talking to Hahn today about replacing some of the parts that come with the kit like the BOV, boost gauge, and fuel pump. Can anyone with this kit recommend parts that I should upgrade before purchasing this kit. I am also thinking of getting that new 2.5" downpipe that ERT is going to be selling.

99'Black GS OZ Edition

I recommend the s-fmu http://www.vortechsuperchargers.com/tech/fmu_sfmu.html
and a good egt gauge
http://www.gadgetseller.com/
there may be some other stuff but id say these are important

Hahn,Wiseco,Eagle,MSD,TurboXs
K&N,mopar,AEM,Greddy,Vortex,apexi and a bunch of other stuff..