[Oldsman]

if you build the motor for no more than 15 psi then if you can get the reflash go for it. but you would also need 2bar MAP and 310cc injectors.

Also the ECU can be reflashed without the car. in the instruction for the s/c it states you can either bring in the car or the ECU for the reflash.

far as the cat.....well with a turbo setup i would go with at least the same size as your exhaust so if running 2.5 then go with 2.5 cat. best case is to remove the cat if you can.