carsound cat question

[1sicprelude]

I have a 94 prelude and recently switched from a f22 to a jdm h22, and I bought a greddy evo 2 exhaust but I bought the one for the vtec engine and now my crappy rusted out cat needs to be replaced. 2 questions

1 What diameter would be best 2.25, or 2.5? im not boosted as of now, but would like to keep that option open for the future.

2 I believe the cat is universal, does anyone know how long this one is versus the oem cat? I know I'll probably need to weld the cat in, but i'd rather not have to add custom pipe if the length is not the same

[SiGNAL748]

well if you plan on boosting later i suppose you could get a 2.5 right now and buy a flange to convert to 2.25, then later remove it for when you boost and go 2.5

not sure this is a good idea, but take it for what its worth.