Which GESI cats for my MS X-pipe?

[Ohnoitseric]

Hi everyone, i’m looking to add some cats to my macht schnell x to quiet it down a bit. It’s being paired up to my Meisterschaft GT2 so rasp is the big issue. My question is, GESI offers their 300/400 cell cats in 2.5 and 3inch in/outlets. I recently figured out that AFE uses their 300 cells (3 inch in/outlet) on their 2.5inch x pipe. Any reason they stepped up to the 3 inch cat? Is there any reason i shouldn’t go with a 2.5inch cat, since the MS x-pipe is 2.5? I don’t see why not but figured i’d ask. I’d also like to keep the CEL off since emissions is still on my mind so would the 400 cells be the better choice (like the AA x-pipe)? Or would the 300 cells do the job and keep the light off? I will be placing them in the primary position. They’re also both the high output epa certified cats. Any input appreciated!