Wondering this too. You don't have to weld the stock heat shield to get it on, there's just a portion you cut off and otherwise you can bolt it on with the factory heatshield bracket that attaches to the upper DP bolts.
Maybe next time I'll try it for shits and giggles. Although, my TBE makes it pretty obvious it's not stock.
I got the stock DP put on today (shoutout to Rebourne for hooking me up). It sounds noticeably tamer...I don't like it. Smog check tomorrow.
Silly question for you all but CA's DMV website isn't very helpful - do I need to get a California license to register my car here? Not really interested in paying for it right now. I'd like to hold on to my WA license for a bit to save some cash.