GridZilla's video: This is the Downpipe I chose for my Type R

Confirmed specs with Two Step Performance and the actual size of the cat is 5 inches (not 4.5 inches) and is a 400 cell count high flow cat (Not 300 cell count). It is however rated up to 1000HP Today we install the Two Step Performance Down Pipe for the FL5 Type R. There are specific reasons why I went this route as mentioned in the video but in short it's a really high quality piece. If you are interested in learning more or picking up one for yourself, please head over to the link below: https://www.twostepperformance.com/products/high-efficiency-downpipe-upgrade-for-2017-2021-honda-civic-type-r-fk8?variant=41423200125060