Here's where I got mine... Super Bright Leds
, look for the 4-led Festoon bulb-it's awesome!
Also got my instrument gauge turn signal bulbs from there.
well i can't tell from grassroots profile pics, but he has a gts and almost all of them have a sunroof. it looks like you don't have a sunroof from your sig, correct me if i'm wrong.
the dome light bulbs for a sunroof celica are different from dome light bulbs for celicas without the sunroof.
like i said..check to make sure you get the right bulbs...especially if you're going to get them over the web.