Haven't watched the vid, but I only have a cat-back. It cost me $750 second hand, they're about $1100 new and actually one of the cheaper cat-back options for this car. Made in the USA and nice quality. It would have gained a few kw, I can feel it however if I did the rest of the exhaust it'd gain a bit more. Planning to do the headers, over-pipe, mid-pipe, might need to think about adding a resonator back in as it's already boomy inside the car under any throttle at all and it'd only get louder and dronier. It had 108rwkw stock, 118rwkw with just a tune so with the cat-back added I'd expect it'd be up around ~125rwkw now. Not bad for an N/A 2.0L auto.
UEL and EL's move the torque band slightly, and although UEL's should lose power they actually don't on this engine. Both make around the same power gain. So realistically it depends if you're looking to eliminate the torque dip or have higher top end and what sound you're looking for. The UEL's do sound pretty hot.