sounds like your doing ok so far, and ive never seen anyone get pulled over for HID's, even if their car didnt come with them from the factory.

as far as the muffler goes, i would go to a muffler shop (i go to rainbow muffler cuz they always do a great job) and have them cut off your factory cat back and they can make you one really cheap. cat-back and muffler welded on my 240 was like 115 i think, and i was VERY pleased with the outcome. so thats a cheap exhaust trick for ya right there.

but like i said, it sounds like your doing ok so far.