[13M5F10]

BPM and Mission Performance are both in CA and highly recommended by members here.

Downpipes: you will get a CEL. I do recommend this as your first choice before changing the exhaust as you will gain power as well as increase the competition exhaust tone and turbo spool. Usually guys start exhaust first and then add downpipes not realizing how drastic it is and end up with very loud cars. Make sure you have the tuner turn off the cold start.

As for downpipes, too many on the market, if I was modding all over again, I'd pick up a Fabworx or Undercover Performance set. Both great and priced reasonably. You might want to check with MSR Performance, I believe @m6beast may have started selling downpipes too.

As for RK, it's been a mix bag, some have had no fitment issues while others have had a ton of issues. I won't get into that debate, let's see how the install goes mentioned above. Hopefully they've corrected the issues as the price is right.