As my name explains, I am new at this. I have a couple of months with a 2012 si sedan and looking to make it sound better and get some more performance out of it as well. I wasn’t sure where to begin though... should I get a downpipe first? Or the exhaust first? Should I get them at the same time? Does one bottleneck the other if one is stock and one is aftermarket? I do live in California so I imagine I would need a catted downpipe. Any advice or help would be appreciated and sorry if the question sounds dumb.