The restriction on the factory exhaust is at the cat. A downpipe would really open up the restriction by eliminating the cat.
Be aware that running no cat is illegal in some states and most likely you will not pass smog. That is why CPE offers the option to weld a high flow cat on the downpipe.
The cat back exhaust will sound more sporty, but to get some real gain you will need the turbo back (ideally with a ECU tune, since the downpipe will lean out the car at Wide Open Throttle)
Hope that helps.
Be aware that running no cat is illegal in some states and most likely you will not pass smog. That is why CPE offers the option to weld a high flow cat on the downpipe.
The cat back exhaust will sound more sporty, but to get some real gain you will need the turbo back (ideally with a ECU tune, since the downpipe will lean out the car at Wide Open Throttle)
Hope that helps.