FI exhaust or valvetronic designs

I’m looking to buy an exhaust for my stock 2018 gtr and I am going back and forth with these two exhaust. So far I’m more with FI but I’d like to get your guys opinion also. AND is the down pipes necessary? or should I keep the stock down pipes when I install the exhaust

https://valvetronic.com/products/nissan-gtr-r35-valved-exhaust?srsltid=AfmBOoojiDrpDJCh3JrJYIKHjGXUMxMgnGav03_cG-zhKPVo8ZvvgzfK

https://www.fi-exhaust.com/web/products/product-detail.jsp?pd_no=PD1652781121736&utm_source=youtube.com&utm_medium=social&utm_campaign=vietho-r35-gtr-fl-2017-upv&utm_content=r35-gtr-fl-2017-upv