Large canister exhausts

JDMcolombia

What are some exhausts (besides greddy) that have large canisters? And what's the big difference (besides weight) between 1 exit vs 2 exit? I'm assuming the single exit would be great for tracking with a single turbo for being lighter and for a more concentrated exhaust flow. Personally, I would prefer a 2 exit exhaust since our vehicles come with it stock.

What's the deal with greddy tic exhaust still being sold? Been reading around and read that it's been discoutinued, although I still see them being sold for brand new?