Do I need to re-tune after installing this header?

Not necessarily. This header flows better than stock, but your engine will adapt to the improved exhaust scavenging. If you're running a tuner or custom ECU tune, you may want your tuner to validate the new flow characteristics. Stock tune runs fine.

Will this header bolt straight to my factory downpipe?

Yes—shorty headers use factory mounting flanges, so connection to your OEM downpipe is direct. No adapters or extensions needed.

Does this come with gaskets and bolts?

Header assembly ships complete. Verify gasket condition before install; reuse if intact or grab a fresh set from your parts supplier if needed. OEM bolts work fine for reinstall.