Headers installed
I wouldn't see it damging anything, I was WAY lean after my catless DP though and I'm assuming I'm going to be rich after my headers. I'll let you guys know this week when we slap her on the dyno.
You won't hurt anything by not tuning your engine it just won't be reaching it's max potenial. 
With just rockers and a cat-back my stock MAF curve was up to 13% low compared to a revised tune (the higher the airflow, the greater the difference). Under WOT, it wasn't actually too lean because of how rich the stock power enrichment table is after about 4,000 RPM - stock commands a 12.1:1 air fuel ratio, whereas I prefer something closer to 12.8 to 13.
I expect the headers and intake upgrade will require a similar adjustment.
I expect the headers and intake upgrade will require a similar adjustment.
you should get a retune for max power but it will run fine without it. If anything it will run a little lean during throttle transitions. Your VE table will need a little adjusting.
