If you don't feel like gutting the precats on your own you can buy pre gutted ems from www.buckshotmotorsports.com just look under misc services and scroll down to optimized EMs. $80 isn't bad if you don't feel confident on doing it youself or don't have the time.

Formerly known as Sneaku I MISS MY BABY!!! '00 Blk CSVT #1087/2150 built 12/23/99