Heated seats are simple, there's lots of aftermarket out there. Most of them are on-off kits, but you can easily make them high-low the same way the OEM's do it, by using a DPDT switch or relay to put the cushion and back elements in parallel for high or series for low.
Forget HID's, they're way more trouble and expense than they're worth. There are lots of plug-and-play H11 LED's out there. If you want to buy American and get a great product with a lifetime warranty, get Diode Dynamics SL2's. DD is the
only US manufacturer of automotive LED's (largely due to idiot DOT restrictions, but that's a story for another thread).
