Yea I would consider saving your money from adding any performance based mod to an AUTO CD5. I had my stock exaust replaced (holes) with an aftermarket on my auto VTI-S and didn't notice one bit of difference in power.

Just my experience but I think you will find many others will tell you round here that any gains will be minimal at best.

if you want to just change the exhaust note, swap out the muffler for a different one and also choose a tip that suits your taste.