With shorties you shouldn't NEED a tune, but your car would benefit from it. If you buy the shorties from Brenspeed, Brent will update your tune for free.
I have the FRPP shorties and no tune was needed... I would definatly go with long tubes if I had it to do over again though.
EDIT: Actually i did my headers, CAI and Diablo tune all in the same weekend so I guess I can't say I didn't tune it but it was the canned performance tune