I did a very quick search and found a few on eBay/Amazon. Most of the kits are for SI's but I'm sure you can find some for the non-SI's.

Usually there is no welding required. unbolt/remove stock exhaust system, bolt this in. It will be plenty loud. Do yourself a favor and search through youtube for people with 2012+ Civic exhausts and take a listen. Find something you like and then go from there. I've never had to have an exhaust welded for any vehicle I've owned. Welding comes in when you purchase universal parts, get into custom set ups or own a vehicle that is not commonly modified (unlike the Civic).

 

 

So I have a d6y7 bottom end with a y8 head(Vtec).. so i tried replacing my O2 sensor today(downstream) on a 1999 Civic EX. The o2 before the catalytic converter and I was told to buy a y8 O2 sensor because it's a y8 harness and the adapter on the new o2 sensor is the same size as the one on the harness and wont clip on. So what I'm thinking is its a y7 harness? Dont mind my stupidity. I'm learning. Someone please help